# 5.70 g of NH4Cl is added to 13.3 g of water. Calculate the molality of the solution

55,318 results, page 68-
## chemistry 1st year, for midterm help

Hi, Can any1 help with theses questions. I need to solve these because there will be similar questions on the midterm for me, coming week. Btw I have tried few. 1. How many milliliters of a 15.0%, by mass solution of KOH (Aq) ( d= 1.14g/mL ) are required

*asked by ur class fella on February 11, 2009* -
## Chemistry

Consider the following reaction AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 (aq) DH = -66 kJ Suppose that 100.0 mL of 0.100M AgNO3 is added to 200.0 mL of 0.100 M NaCl in a coffee cup calorimeter. Assuming that the initial temperature of the solution is

*asked by Mahnoor on November 15, 2014* -
## chemistry

What is the predicted change in the boiling point of water when 4.00 g of barium chloride (BaCl2) is dissolved in 2.00 kg of water? Kb of water = 0.51°C/mol molar mass BaCl2 = 208.23 g/mol i value of BaCl2 = 3 A. 0.0016°C B. -0.0049°C C. -1.0°C D.

*asked by lu on January 23, 2017* -
## Can anyone help me with a physics question?

A water tank has a volume of 100m^3. A square pipe leading to a pump is designed to completely replace all water in 20 minutes. Caluclate the length of a side of the square if the water is travelling at 5.0m/s through the square pipe.

*asked by Rob on March 16, 2010* -
## math

A water system of 2 in.(inside diameter) pipe, having a length of 1/4 mile, is to be flushed with a volume of water equal to twice that contained in the system. how much water (gallons) must be flushed through the system? (note: one cubic foot=7.481gal.)

*asked by Wilfredo on February 11, 2013* -
## science

Erin must perform a science experiment. She needs to dissolve 10 g of salt in 250 ml of water. She measures the water incorrectly and dissolves the 10 g of salt in 350 ml of water. Now she has no more salt. Explain what Erin can do to make the solution

*asked by astrid on April 29, 2008* -
## Chemistry

the heat of fusion water is 335J/g,the heat of vaporization of water is 2.26kJ/g, the specific heat of water is 4.184J/deg/g. how many grams of ice at 0 degrees could be converted to steam at 100 degrees C by 9,574J

*asked by Randy on April 27, 2012* -
## Chemistry

Although water and ammonia differ in molar mass by only one unit, the boiling point of water is over 100 degrees C higher than that of ammonia. What forces in liquid water that do not exist in liquid ammonia could account for this observation?

*asked by Joe Schmo on April 27, 2011* -
## Science please help

Some of the water flows over the dam and is converted to energy, some water evaporates into the air. What spheres does the water, or hydrosphere interact with this example? a. Geosphere and atmosphere B. Atmosphere and biosphere C. Crysophere and

*asked by Steph on January 12, 2015* -
## Physics

A battery (ε= 6.20V, r = 0.100Ω) is connected to three light bulbs in parallels (R1= 6.00Ω, R2= 9.00Ω, R3= 18.0Ω). a) Calculate the current delivered by the battery. (b) Calculate the potential difference across the load. (c) Calculate the current in

*asked by GUCCIxLV on December 13, 2018* -
## chemistry

While researching energy values of fuels, a chemist designed an experiment to find out the heat of combustion of pentane. Using the known hexane heat of combustion of hexane = 4650kJ/mol and the data below calculate the heat of combustion of pentane. Set

*asked by sarah on March 28, 2010* -
## chemistry

While researching energy values of fuels, a chemist designed an experiment to find out the heat of combustion of pentane. Using the known hexane heat of combustion of hexane = 4650kJ/mol and the data below calculate the heat of combustion of pentane. Set

*asked by sarah on March 28, 2010* -
## algebra

Rebecca drinks at least 7 cups of water each day. So far,she drank 1.5 cups. She will drink the rest of her water from a bottle that holds 1.5 cups. Write an inequality for the minimum number of bottles of water she will drink.

*asked by Anonymous on April 3, 2013* -
## Math

PLEASE HELP: A bathtub has a capacity of 42 gallons and is completely full of water. Ten gallons of water are drained out. Enter the percentage of gallons of water left in the bathtub. Round your answer to the nearest hundredth.

*asked by jwalkerjess on September 17, 2015* -
## Science

In an experiment, 200 g of aluminum at 100degrees celsius is mixed with 50.0g of water at 20.degrees celsius, with the mixture thermally isolated.(a)What is the equilibrium temperature?What are the entropy changes of(b)the aluminum,(c)the water,and(d)the

*asked by lungi on August 23, 2010* -
## physics

A jet of water squirts out horizontally from a hole near the bottom of the tank, as seen in the figure below. Assume that y = 1.19 m and x = 0.544 m. What is the speed of the water coming out of the hole? The hole has a diameter of 3.06 mm. What is the

*asked by Jackie on March 5, 2012* -
## chem

Calcium metal and water produce hydrogen gas. If the volume of wet gas collected over water is 95.0 mL at 20 °C and 758 mm Hg, what is the volume of dry gas at STP conditions? (The vapor pressure of water at 20 °C is 17.5 mm Hg.)

*asked by nurse on April 3, 2013* -
## Trigonometry

The depth d in feet of the water in a bay at is given by d(t) = 3/2 sin (5πt/31) + 23 where t is time. Graph the depth of the water as a function of time. What is the maximum depth of the water to the nearest tenth of a foot? (Enter only the number.)

*asked by Mariah on October 2, 2014* -
## algebra

Rebecca drinks at least 7 cups of water each day. So far,she drank 1.5 cups. She will drink the rest of her water from a bottle that holds 1.5 cups. Write an inequality for the minimum number of bottles of water she will drink.

*asked by Anonymous on April 3, 2013* -
## physics

A person jumps off a diving board 4.6 m above the water's surface into a deep pool. The person's downward motion stops 1.6 m below the surface of the water. Estimate the average deceleration (magnitude) of the person while under the water.

*asked by Anonymous on January 9, 2012* -
## reading

Please help Claim lead in drinking water with harm humans Which of the following is support this claim a. After use water that contain high level of lead, people note that their toothbrush turned yellow b. After use water that contain high level of lead,

*asked by lan on March 26, 2018* -
## Chem17

Consider the following reaction at equilibrium: C(s) + H2O(g) CO(g) + H2(g) Predict which of these stresses which cause the equilibrium system to shift towards the reactant side (to the left). (There may be more than one correct answer - choose ALL of the

*asked by Ryan on May 2, 2011* -
## physics

A fire hose ejects a stream of water at an angle of 31.7 ° above the horizontal. The water leaves the nozzle with a speed of 29.2 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by Kristyn on March 25, 2015* -
## physics

A fire hose ejects a stream of water at an angle of 38.3 ° above the horizontal. The water leaves the nozzle with a speed of 29.5 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by chelsea on January 31, 2012* -
## Physics

A fire hose ejects a stream of water at an angle of 35.8 ° above the horizontal. The water leaves the nozzle with a speed of 21.9 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by Nicole on December 13, 2015* -
## Physics

A fire hose ejects a stream of water at an angle of 29.0° above the horizontal. The water leaves the nozzle with a speed of 31.0 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by Anonymous on September 18, 2012* -
## Math

A rectangular glass tank is half filled with water. The measurements of the tank are 30cm in height, 25cm in length and 20cm in width. How many litres of water will raise the water level in the glass tank by 5cm?

*asked by Kate on September 12, 2017* -
## physics

A fire hose ejects a stream of water at an angle of 36.4 ° above the horizontal. The water leaves the nozzle with a speed of 20.1 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by Allyson on September 10, 2013* -
## physics

A fire hose ejects a stream of water at an angle of 32.2 ° above the horizontal. The water leaves the nozzle with a speed of 26.5 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by louis aaaa on June 23, 2013* -
## chemistry

A piece of metal weighing 26g is immersed in a quantity of water in a graduated cylinder. The initial volume of the water was 16.0 ml and volume of water plus metal is 22.0 ml. The density of metal in g/ml is? If you get this right i will hand you over my

*asked by Noel on July 21, 2010* -
## math

points) You arrive home to find that your 55 foot by 20 foot basement has 6 inches of water in it. a) If 1 cubic foot of water is about 7.48 gallons, how much water will you be pumping out of your basement? Express your answer rounded to the nearest tenth

*asked by joie on September 23, 2017* -
## physics

A fire hose ejects a stream of water at an angle of 31.5 ° above the horizontal. The water leaves the nozzle with a speed of 24.3 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by ray on September 19, 2012* -
## maths

A water tank has the shape of a rectangular prism of base 50 cm2. This tank is being filled at the rate of 12 liters per minutes. Find the rate at which the height of the water in the water tank increases; express your answer in millimeters per second.

*asked by LARA on February 3, 2014* -
## Physics/trig

A fire hose ejects a stream of water at an angle of 33.6 ° above the horizontal. The water leaves the nozzle with a speed of 29.6 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by Jenna on October 9, 2015* -
## physics

A fire hose ejects a stream of water at an angle of 31.7 ° above the horizontal. The water leaves the nozzle with a speed of 29.2 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by Kristyn on March 25, 2015* -
## physics

A fire hose ejects a stream of water at an angle of 35.0º above the horizontal. The water leaves the nozzle with a speed of 25.0 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by paul on September 19, 2013* -
## calculus

A water trough is 8m long and its cross-section is an isosceles triangle which is 60cm wide at the top, and the height is 60cm. The trough is not full. Give an expression for V, the volume of water in the trough in cm^3, when the depth of the water is d

*asked by Teresa on October 15, 2017* -
## physics

A fire hose ejects a stream of water at an angle of 33.4 ° above the horizontal. The water leaves the nozzle with a speed of 20.1 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by V on February 5, 2015* -
## Physics

A fire hose ejects a stream of water at an angle of 30.9° above the horizontal. The water leaves the nozzle with a speed of 26.5 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the

*asked by Cetris on February 28, 2015* -
## math

Inside a long empty cylinder with radius R = 25 cm is put a long solid cylinder with radius r = 10 cm such that the bases of the two cylinders are attached. Then water is poured in the remaining empty region of the first cylinder until the height of the

*asked by emy on February 22, 2015* -
## Chemistry

A 13.0-g sample of ice at -13.0°C is mixed with 112.0 g of water at 80.0°C. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. The heat capacities of H2O(s) and H2O(l) are 2.08 and 4.18 J/g · °C, respectively, and

*asked by Katrina on February 13, 2011* -
## Science: Chemistry

Pentane (C5H12) burns in oxygen to produce carbon dioxide and water. C5H12(g)+8O2(g)→5CO2(g)+6H2O(g) Calculate the mass of CO2 that can be produced if the reaction of 38.5 g of pentane and sufficient oxygen has a 58.0 % yield.

*asked by Alex on November 15, 2015* -
## Chemistry

A 14.0-g sample of ice at -18.0°C is mixed with 122.0 g of water at 87.0°C. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. The heat capacities of H2O(s) and H2O(l) are 2.08 and 4.18 J/g · °C, respectively, and

*asked by Janesa on March 9, 2012* -
## Chemistry

A 19.6 g sample of ice at -10.0°C is mixed with 100.0 g of water at 75.4°C. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. The heat capacities of H2O(s) and H2O(l) are 2.08 and 4.18 J g-1 °C-1, respectively,

*asked by Anonymous on November 23, 2010* -
## chemistry

A 13.0-g sample of ice at -13.0°C is mixed with 105.0 g of water at 78.0°C. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. The heat capacities of H2O(s) and H2O(l) are 2.08 and 4.18 J/g · °C, respectively, and

*asked by layla on October 15, 2011* -
## biology

A 28.0-g sample of ice at -18.0°C is mixed with 124.0 g of water at 85.0°C. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. The heat capacities of H2O(s) and H2O(l) are 2.08 and 4.18 J/g · °C, respectively, and

*asked by layla on October 15, 2011* -
## Chemisrty

A 10.0 g sample of ice at -14.0°C is mixed with 124.0 g of water at 81.0°C. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. The heat capacities of H2O(s) and H2O(l) are 2.08 and 4.18 J/g°C, respectively, and the

*asked by Nancy on December 9, 2012* -
## Physics - URGENT

A ball is thrown horizontally of a cliff. If the initial speed of the ball is 17 m/s and the cliff is 77 m high, how far from the base of the cliff will the ball land in the water below? Calculate the answer in meters (m) and rounded to three significant

*asked by Anonymous on September 16, 2015* -
## Chemistry-DrBob222

A 1.0 L ball containing Ar at 5 atm is connected to a 10.0 L ball containing N2 at 2atm. A)Calculate the partial pressures and mole fractions of Ar and N2 after the valve is opened and the gases are allowed to mix (they fill the balls on both sides). My

*asked by Student on March 11, 2016* -
## Chemistry

A 1.0 L ball containing Ar at 5 atm is connected to a 10.0 L ball containing N2 at 2atm. A)Calculate the partial pressures and mole fractions of Ar and N2 after the valve is opened and the gases are allowed to mix (they fill the balls on both sides). My

*asked by Nevaeh on March 12, 2016* -
## Chemistry-DrBob222

A 1.0 L ball containing Ar at 5 atm is connected to a 10.0 L ball containing N2 at 2atm. A)Calculate the partial pressures and mole fractions of Ar and N2 after the valve is opened and the gases are allowed to mix (they fill the balls on both sides). My

*asked by Nevaeh on March 11, 2016* -
## Health Finance

Question Details Consider the following 2007 data for Newark General Hospital (in millions of dollars): Static Flexible Actual Budget Budget Results Revenues $4.7 $4.8 $4.5 Costs 4.1 4.1 4.2 Pro?ts 0.6 0.7 0.3 a. Calculate and interpret the pro?t variance.

*asked by molamidi on January 26, 2012* -
## physics

A rock climber stands on top of a 56m -high cliff overhanging a pool of water. He throws two stones vertically downward 1.0s apart and observes that they cause a single splash. The initial speed of the first stone was 2.5(m/s) How long after the release of

*asked by Nicole on October 2, 2012* -
## Chemistry

The lab we are doing is: Determining the ENTHALPY of a Chemical Reaction. There are three reactions. Reaction 1: NaOH + HCl, Reaction 2: NaOH + NH4Cl, and Reaction 3: HCl + NH3. I found the max temp, initial temp, and temp change of each reaction. Can you

*asked by Rina on October 29, 2017* -
## CHEMISTRY

A 1.575 g sample of ethanedioic acid crystals, H2C2O4. xH20 was dissolved in water and made up to 250cm^3 . One mole of the acid reacts with two moles of NaOH. In a titration, 25.0 cm^3 of this solution of acid reacted with exactly 15.6 cm^3 of 0.160 mol/

*asked by Jack on July 9, 2016* -
## chem

what happens when NaCl(s) is dissolved in water? (1)Cl-ions are attracted to the oxygen atoms of the water (2)Cl-ions are attracted to the hydrogen atoms of the water. (3)Na+ions are attracted to the hydrogen atoms of the water. (4)no attractions are

*asked by Tina on February 13, 2011* -
## MMSS

the volume of 500g sealed packet is 350 cubic centimeters. Will the packet float or sink in the water if the density of water is 1 gm per cubic meter ? What will be the mass of water displaced by this packet

*asked by ABHISHEK on January 20, 2013* -
## science

________ causes deep currents. a) Heavy, salty water sinking in the ocean. b) evaporation of seawater by the sun's rays c) less salty water rising to replace heavy, salty water d)all of the above d

*asked by pam on September 2, 2010* -
## Calculus

A spherical balloon with radius 3 inches is partially filled with water. If the water in the balloon is 4 inches deep at the deepest point, how much water is released when the balloon hits the wall and breaks?

*asked by Andy on February 18, 2015* -
## chemistry

a 100.00 mL sample of water has an initial temperature of 20.0 degrees C. The water is heated, and after 5 minutes its temperature is 50 degrees C. approximately how much energy was absorbed by the water? (the specific heat of wter is 4.18 J/g. degrees C

*asked by kelly on September 3, 2011* -
## Chemistry

When a balloon filled with 1.249 g of hydrogen explodes, the hydrogen reacts with 9.99 g of oxygen to form water vapor. Assuming water vapor is the only product formed, how much water vapor is produced?

*asked by Jackie on March 25, 2016* -
## math,eng,phy,chem,bio,geography,economics

in an experiment of oxgen to hydrogen in water molecule. 9g of iron were heated in a current of hydrogen,6.5g of iron and 2.8g of water were formed using this data. determine the proportion by mass of oxygen to hydrogen in water

*asked by joyce on January 17, 2016* -
## math

A water trough is 4 m long and its cross-section is an isosceles trapezoid which is 210 cm wide at the bottom and 280 cm wide at the top, and the height is 70 cm. The trough is not full. Give an expression for V, the volume of water in the trough in cm^3,

*asked by j on October 15, 2012* -
## physics

A fire hose a stream of water at an angle of 35degree above the horizontal. The water leaves the nozzle with a speed 25m/s. Assuming that the water behave like a projectile ,how far from a building should the fire hose be located to hit the highest

*asked by afika on May 9, 2016* -
## Maths

A water tank has the shape of a rectangular prism of base 50 cm2. This tank is being filled at the rate of 12 liters per minutes. Find the rate at which the height of the water in the water tank increases; express your answer in millimeters per second. I

*asked by Elise on July 14, 2015* -
## Calculus

If water is lost at 20ft^3/day when W= 10,000 ft^3 then the leakage rate constant in the differential equation is 20/10,000 or 0.002. Suppose that water flows in at F= 200,000 ft^3/day. How much water would you predict in the lake after 100 days?\ W =

*asked by Lara on February 7, 2010* -
## Chemistry

What happens to the sample's reported water content if the salt decomposes yielding a volatile product? If the water is not completely removed from the salt during the heating process, will the reported water-to-salt mole ratio be high or low? Explain

*asked by Allison on December 6, 2010* -
## Differential calculus

reservoir has the shape of a right-circular cone. The altitude is 10 feet, and the radius of the base is 4 ft. Water is poured into the reservoir at a constant rate of 5 cubic feet per minute. How fast is the water level rising when the depth of the water

*asked by Mohammed on November 26, 2016* -
## chemistry

The enthalpy change for the solution process when solid sodium hydroxide dissolves in water is -44.4 kJ/mol. When a 13.6 g sample of NaOH dissolves in 250.0 g of water in a coffee-cup calorimeter, the temperature increases from 23.0 o C to __________ o C.

*asked by Anonymous on November 15, 2010* -
## Chemistry

At -15.0 C, what is the maximum mass of fructose (C6H12O6) you can add to 3.00 kg of pure water and still have the solution freeze? Assume that fructose is a molecular solid and does not ionize when it dissolves in water. I'm confused on how you pick the

*asked by Tracy on February 16, 2012* -
## Maths

A bucket holds 6 litres of water. A paddling pool is in the shape of a cuboid with dimensions 700mm x 1800mm x 3000mm. How many buckets of water would be required to fill the pool to the brim? If the pool has a leak and loses water at the rate of 20ml per

*asked by Anonymous123 on April 17, 2016* -
## Mathematics

At Harlan County Damn in Nebraska, the U.S. Bureau reports that the storage content of the reservoir decreased from 117,811 acre-feet (38.4 billon gallons of water) on Septmber 6, 2006 to 115,579 acre-feet (37.7 billion gallons of water) on October 6,

*asked by Kevin on September 8, 2008* -
## 7th grade math

1. Price of the dolls: $12.99 A. Price of the dolls with a 5% sales tax. Show all of your work! [4 points] B. A discount of 20% is applied to the doll’s original price of $12.99. What is the price of the dolls with the discount applied to $12.99 + 5%

*asked by Delilah on November 27, 2012* -
## Chemistry

In a crazy scenario, the Oylan Vinegar Company has 10,000 gallons of vinegar with 0.622% concentration. This vinegar solution cannot be sold because it's too weak, but the plant manager can't bear to discard it. OVC also has a large batch of vinegar that

*asked by Mads on March 13, 2016* -
## Chemistry PLS HELP!!!

A student collects oxygen gas by water displacement at a temperature of 17 Celsius. A barometer reads 92.3 kPa. What is the pressure of the water vapor? Look it up on a water vapor pressure chart. What is the pressure of the oxygen gas? (Answer: ~14.0 mmHg

*asked by Ana on March 28, 2016* -
## Chemistry

Gold can be recovered from sea water by re- acting the water with zinc, which is refined from zinc oxide. 2 ZnO(s) + C(s) −→ 2 Zn(s) + CO2(g) 2 Au3+(aq) + 3 Zn(s) −→3 Zn2+(aq) + 2 Au(s) The zinc displaces the gold in the water. What mass of gold

*asked by Renee on March 16, 2014* -
## molarity

calculate the molarity of k+ in a soln prepared by adding .2L of .200M K3PO4 and 75.0mL of .5M K3PO4. assume volumes are additive. A few of steps here and more than one way to answer the problem You need to calculate the total number of moles of K3PO4 from

*asked by Christine on April 5, 2007* -
## math

Hayden had 2 1/2 gallons of water in his watering can. The seed packet said to use 1/4 of a gallon for peppers and 5/8 of a gallon for tomatoes. Hayden then used some of the water for lettuce. If Hayden had 3/4 gallons of water left over, about how much

*asked by carla on August 25, 2016* -
## Physical Science

The density of sea water is slightly higher than that of fresh water. The higher density is due to the fact that sea water contains salts such as sodium choride and magnesium chloride. Suppose you have a container that holds 5.00 kg of freshwater, which

*asked by Spazzo on August 24, 2010* -
## Math

My overall average right now is a 77%. A test exam of 67 has to be added in. That exam itself is only 10% added to final. Can someone help and tell me what my final will average out after 10% of the 67 will be? Thank you

*asked by Nursing student on June 25, 2015* -
## Biology

When a teapot boils, we see a white cloud rising from the spout. The white cloud is composed of: A. water in the liquid phase B. water in the gaseous phase c. water molecules coming apart to from H+ and OH- ions D. H+ and OH- ions coming together to form

*asked by Anonymous on March 16, 2014* -
## math help pls pls pls

Water coming out from a fountain is modeled by the function f(x) = −x2 + 8x + 2 where f(x) represents the height, in feet, of the water from the fountain at different times x, in seconds. What does the average rate of change of f(x) from x = 1 to x = 4

*asked by Oscar on April 20, 2016* -
## chemistry--last time i promise

CO(g) + H2O(g)-->CO2 + H2 (g) reaction occurs in a 2.0 Ll reactor at 800 degrees celsius. The reaction conditions are such that a complete conversion of reactants into products results. The reactor is charged initially with 5.0 atm of CO and 8.0 atm of

*asked by alexis on May 3, 2015* -
## CHEMISTRY

brass is a subtitutional alloy consisting of a solution of copper and zinc. a particulae sample of red brass consisting of 80% copper and 20% zinc by mass has a density of 8750kg/m^3. a. what is the molality of zinc in the solid solution and B. what is the

*asked by lulu78 on October 14, 2010* -
## physics

For a helium atom containing two protons, two neutrons and two electrons: A)Calculate the first energy levels(n=1,2,3,4,5)(answers (-54.4eV, -6.04eV, -3.4eV, -2.176eV) b)Calculate the frequency in Hz of a proton emitted from n=2 to n=1 (answer 9.86x

*asked by chanty on December 4, 2012* -
## physics university

For a helium atom containing two protons, two neutrons and two electrons: A)Calculate the first energy levels(n=1,2,3,4,5)(answers (-54.4eV, -6.04eV, -3.4eV, -2.176eV) b)Calculate the frequency in Hz of a proton emitted from n=2 to n=1 (answer 9.86x

*asked by chanty on December 3, 2012* -
## Science

I conducted an experiment of the heat of combustion for three alcohol fuels, methyl, propyl and ethyl. The results were: Methyl - mass before was 231.81g temp of water before heating was 15 deg c. temp of water after heating was 40 deg c. mass of methyl

*asked by Paul on November 8, 2010* -
## chemistry (moles)

2.5g of a mixture of anhydrous BaOH and BaCl2 was dissolved in distilled water and made up to 250cm3. 20cm3 of this solution required 19cm3 of 0.1moldm3 of dilute nitric acid for complete reaction. Calculate the percentage by mass of BaCl2 present in the

*asked by joseph on January 21, 2016* -
## Chemistry

Calculate the total heat (in Joules) needed to convert 1.602 x 101 grams of ice at -1.383oC to liquid water at 8.554 x 101oC. Melting point at 1 atm 0.0oC Cwater(s) = 2.09 J/goC Cwater(l) = 4.18 J/goC delta Hofus = 6.02 kJ/mol

*asked by Devin on January 12, 2015* -
## Science

The solubility of potassium nitrate is 40 at 30 degree celcius. Calculate the mass of water required to make a saturated solution by dissolving 15 gram of potassium nitrate at that temperature. Could u guys help me to get answer of this question. Plz help

*asked by Dõniyā on March 29, 2016* -
## Chemistry - Please help!!

I did a lab for Organic Chemistry We did a simple distillation of an unknown alcohol to determine the boiling point, which was found to be 74*C The four possibilities for the unknown were methanol, ethanol, 1-propanol and 2-propanol. So from the boiling

*asked by Laura on October 5, 2010* -
## Chemistry

I did a lab for Organic Chemistry We did a simple distillation of an unknown alcohol to determine the boiling point, which was found to be 74*C The four possibilities for the unknown were methanol, ethanol, 1-propanol and 2-propanol. So from the boiling

*asked by Laura on October 5, 2010* -
## physics

A ball is thrown horizontally of a cliff. If the initial speed of the ball is 24.0 m/s and the cliff is 124.0 m high, how far from the base of the cliff will the ball land in the water below? Calculate the answer in meters (m) and rounded to three

*asked by Dalia on January 31, 2017* -
## classical mechanics

enturi Flow Meter (19 points possible) A Venturi flow meter is used to measure the the flow velocity of a water main. The water main has a diameter of 40.0 cm, and the constriction has a diameter of 10.0 cm. The two vertical pipes are open at the top, and

*asked by socorro on December 10, 2013* -
## math

A group of people planned to contribute equally towards a water project which needed Ksh 200,000 to complete, however, 40 members of the group without from the project. As a result, each of the remaining members was to contribute Kshs 2,500. (a) Find the

*asked by kudu on February 21, 2015* -
## Chemistry

Heat from burning a fuel is absorbed by a copper calorimeter. The calorimeter has a mass of 81.34 g and contains 200.0 g of water initially at 21 degrees Celsius. a) How much heat was absorbed by the calorimeter and the water if the final temperature of

*asked by lomonoyan on October 20, 2016* -
## AP Calculus.HELP!

Water runs into a conical tank with radius 5 and altitude 10 at a constant rate of 2 cu.ft. per min. How fast is the water rising in the tank at any instant? You want dh/dt, given dV/dt. so write an equation relating V to h. V= 1/3 Areatop*h, in this case

*asked by Sarah on October 26, 2006* -
## physics

the velocity of the water jet discharging from the orifice can be obtained from v = (2gh)^(1/2), where h = 2m is the depth of the orifice from the free water surface. determine the time for a particle of water leaving the orifice to reach point B and the

*asked by - on April 3, 2011* -
## NU

The end of a thin glass-wall tube with an inside diameter of 1-mm is inserted into a reservoir of pure water with a temperature of 25 degree C. What is the surface tension (adhesoin) force on the water inside the tube? To what height will the water rise in

*asked by LaToya on March 17, 2011* -
## chemistry

can some one help me with a few chem questions please. A chunk of iron weighs 4.32 g. a) How many iron atoms are there in this sample? 55.85 g Fe = 1.00 mol Fe = 6.022 x 1023 atoms Fe b) How many moles of iron are there in this sample? 2. . You have a

*asked by anna on November 12, 2015*