Tuesday

June 30, 2015

June 30, 2015

Total # Posts: 998

**Stoichiometry chem**

Just to recap: I divide the grams of the compound by its molar mass. From there, I do the mol conversion from CaCO3 to C and that will by my answer.
*June 27, 2015*

**Stoichiometry chem**

If there is one mole of Carbon for every CaCO3, all I had to do was divide it and that would be my answer (2.498)? What if it was 2 moles of carbon instead of one, what would I have to do then?
*June 27, 2015*

**Stoichiometry chem**

How many moles of carbon are found in 250.0 g of CaCO3? I started off with finding the molar mass of CaCO3, which is 100.09g. From there I divided 250g by 100.09g, but I have no idea what to do from there.
*June 27, 2015*

**Science **

When you change the dna code to mRNA, will A become U or T?
*June 14, 2015*

**math**

A circle of radius 2 is externally tangent to a circle of radius 8. Compute the length of their common tangent.
*June 6, 2015*

**math**

Solve for all real values of x is 9^x+2=240+9^x THIS ONE IS HARD
*June 6, 2015*

**Math**

Joan's stamp collection consists of three books. Two tenths of her stamps are on the first book, several sevenths are in the second, and there are 303 stamps in the third book. How many stamps are there in Joan's collection?
*June 6, 2015*

**math**

In triangle ABC, AC=BC. The point D is on BC such that AB=AD=DC. Compute the measure of angle C. I'm not sure how to do this...
*June 6, 2015*

**Chemistry**

when I do m=M*n I get a really high Number which I don't think is right.
*June 4, 2015*

**Chemistry**

How many grams of zinc metal are required to produce 2.00 L of hydrogen gas at STP according to the chemical equation shown below? Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
*June 4, 2015*

**prealgebra**

find the slope of a road that rises 5 feet vertically for every 45-foot horizontal increase.
*May 14, 2015*

**Algebra 2 Honors**

Hey, we recently started a topic in class that I don't understand well, I just want to post 6 of the problems and ask if they're right or not (some of them I have no idea how to do). 1. If a varies directly as b and b = 18 when a = 27, find a when b = 10. For this I ...
*May 13, 2015*

**Organic chemistry**

What is the product formed when phtalic anhydride reactors with D2O/D+? Thank you in advanced!
*May 13, 2015*

**Chemistry Gas Law**

How many grams of Mg must react with HCl in order to produce 40.0 ml of hydrogen gas at 22 degrees celsius and 1.02 bar? If the magnesium ribbon weighs 1.83mg/mm, how many mm of the ribbon will you require? Thanks in advance for your help!!
*May 12, 2015*

**Math**

The tail on Alex's dog is 5 1/4 inches long this like this between which 2 inch March on a ruler
*May 12, 2015*

**Trig identities**

Thank you so much!
*May 12, 2015*

**Trig identities**

Sin x/[1-cos(-x)] = csc x + cot x Please Verify the Identity. I have been going in circle with this one... Just a hint would be nice. Thank you.
*May 12, 2015*

**chemistry**

Calculate the weight in grams of potassium hydrogen phthalate (KHP, KHC2H3O2, MW 202.2 g/mole) required to neutralize 25.00 ml of 0.1 M NaOH solution.
*April 15, 2015*

**chemistry**

Describe in detail how you would prepare 500 ml of 0.1 M HCl from 6 M HCl stock solution.
*April 15, 2015*

**chemistry**

Describe in detail how you would prepare 1000 ml of 0.1 M NaOH from 6 M of NaOH stock solution.
*April 15, 2015*

**Maths help**

W= rad/s and a = 0.6. My mistake Very sorry reiny it's just that I'm in desperate need of help and no one Is answering my questions. Could you please help me?
*April 12, 2015*

**Maths help **

The angle of a rotating shaft turns in t seconds is given by theta= ω+1/2at^2 and it is given that ω=3 2 rad/s and α=0.6 rad/s to complete θ=4 radians. Determine the time taken to complete θ=4 radians.
*April 12, 2015*

**Maths help**

Two resistors in series, R1 and R2, have a total resistance of 1,600 ohms. The resistance of R2 is 560 ohms less than twice R1. Find the resistance of R1 and R2.
*April 12, 2015*

**Maths help**

The law connecting friction F and load L for an experiment is of the form F =aL+b, where a and b are constants. When F =5.6, L=8.0 and when F =4.4, L=2.0. Find the values of "a" and "b "and the value of F when L=6.5.
*April 12, 2015*

**Maths help**

A manufacture finds the total cost "C" for a product is expressed by C=3x2-8, and the total revenue "R" by R=3x-2, where x is the number of units sold. What is the breakeven point (where total cost=total revenue) to the nearest unit?
*April 12, 2015*

**Maths help **

Two flares are launched from a life raft. The height h of the first flare in metres above the sea is modelled by the formula h1= t2+t+1meters,and the second flare is h2=4-t where t is the time 12 in seconds after the flare is launched. Determine (i) Time taken and (ii) Height ...
*April 12, 2015*

**Physics**

1. A point on the edge of a large wheel of radius 0.45 meters moves through an angle of 170o at a constant angular velocity of 0.25 radians/sec. . (a) Find the length (in meters) of the arc described by the point. (b) Find the linear velocity (in m/sec) of a point located on ...
*April 6, 2015*

**Biology**

8) Describe the difference between a prosthetic group, cofactor, and coenzyme; provide an example of each.
*March 24, 2015*

**Biology**

What does b-mercaptoethanol do to secretory proteins?If you forgot to add b-mercaptoethanol to a secretory protein, would the protein's migration likely speed up or slow down? Why?
*March 22, 2015*

**Biology**

For each of the following characteristics, will the migration of the protein speed up, slow down, or remain unchanged if you do not add SDS? a)increase molecular weight of protein b) increase concentration of acrylamide c)decrease charge on protein d) increase surface area of ...
*March 22, 2015*

**Biology**

What does b-mercaptoethanol do to secretory proteins?If you forgot to add b-mercaptoethanol to a secretory protein, would the protein's migration likely speed up or slow down? Why?
*March 22, 2015*

**Biology**

What does b-mercaptoethanol do to secretory proteins?also...If you forgot to add b-mercaptoethanol to a secretory protein, would the protein's migration likely speed up or slow down? Why?
*March 22, 2015*

**Biology**

3) For each of the following characteristics, will the migration of the protein speed up, slow down, or remain unchanged if you do not add SDS? a)increase molecular weight of protein b) increase concentration of acrylamide c)decrease charge on protein d) increase surface area ...
*March 22, 2015*

**Biology**

What does b-mercaptoethanol do to secretory proteins?also...If you forgot to add b-mercaptoethanol to a secretory protein, would the protein's migration likely speed up or slow down? Why?
*March 22, 2015*

**Biology**

3) For each of the following characteristics, will the migration of the protein speed up, slow down, or remain unchanged if you do not add SDS? a)increase molecular weight of protein b) increase concentration of acrylamide c)decrease charge on protein d) increase surface area ...
*March 22, 2015*

**Biology**

also...If you forgot to add b-mercaptoethanol to a secretory protein, would the protein's migration likely speed up or slow down? Why?
*March 20, 2015*

**Biology**

What does b-mercaptoethanol do to secretory proteins?
*March 20, 2015*

**Biology**

3) For each of the following characteristics, will the migration of the protein speed up, slow down, or remain unchanged if you do not add SDS? a)increase molecular weight of protein b) increase concentration of acrylamide c)decrease charge on protein d) increase surface area ...
*March 20, 2015*

**Algebra 2**

Find a third-degree polynomial equation with rational coefficients that has roots -1 and i+1
*March 13, 2015*

**Physics**

The coefficient of static friction between the m = 3.75-kg crate and the 35.0° incline of the figure below is 0.320. What minimum force vector F must be applied to the crate perpendicular to the incline to prevent the crate from sliding down the incline?
*March 10, 2015*

**Statistics**

A history class is comprised of 5 female and 8 male students. If the instructor of the class randomly chooses 8 students from the class for an oral exam, what is the probability that 2 female students and 6 male students will be selected? Round your answer to decimal places.
*March 10, 2015*

**Chemistry**

The mass of spectrum of 2,4-dimethylpentane shows peaks at m/z 43, 57, and 85. Show the fragments which produce these peaks.
*March 5, 2015*

**Chemistry**

Consider the following reaction: CO(g)+H2O(g)⇌CO2(g)+H2(g) Kp=0.0611 at 2000 K A reaction mixture initially contains a CO partial pressure of 1348torr and a H2O partial pressure of 1780torr at 2000 K. Calculate the equilibrium partial pressure of CO2. Calculate the ...
*February 25, 2015*

**Biology**

describe how a population is thought to evolve through natural selection. Provide an example (specifically, the peppered moth)
*February 20, 2015*

**Chemistry**

name all the possible isomers of methyl nitrobenzoate and nitroacetanilide which can be formed
*February 11, 2015*

**Organic Chem**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Organic Chem**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Organic Chemistry**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Chemistry**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Chemistry**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Chemistry**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Chemistry**

A solution of 4-methyl-3-penten-2-one in ethanol shows an absorbance of 0.52 at 236 nm in a cell with a 1-cm light path. Its molar absorptivity in ethanol at that wavelength is 12,600 M^-1 cm^-1. What is the concentration of the compound?
*February 11, 2015*

**Chemistry**

A solution of 4-methyl-3-penten-2-one in ethanol shows an absorbance of 0.52 at 236 nm in a cell with a 1-cm light path. Its molar absorptivity in ethanol at that wavelength is 12,600 M^-1 cm^-1. What is the concentration of the compound?
*February 11, 2015*

**Chemistry**

Why does the carotene elute from the column before the chlorophylls?
*February 11, 2015*

**Chemistry**

Why should a mixture to be separated by column chromatography be introduced onto the column in a minimum amount of solvent?
*February 11, 2015*

**Chemistry**

Arrange the following compounds in order of decreasing ease of elution from a column of silica gel: a) 2-octanol; b) 1,3-dichlorobenzene; c) tert-butylcyclohexane; d) benzoic acid
*February 5, 2015*

**Chemistry**

name* Thanks for help DR. Bob
*February 4, 2015*

**Chemistry**

Okay i'll keep my answers the same. What do you think is the answer. Tert-butylcyclohexane > 1,3-dichlorobenzene > 2-octanol > benzoic acid
*February 4, 2015*

**Chemistry**

What precautions must be taken when you introduce a mixture of compounds to be separated onto a liquid chromatography adsorbent column?
*February 4, 2015*

**Chemistry**

oh no man. i just want different answers to see if the answers are right. And if people agree. I just don't want to take chances. Do you have a background in chemistry or something? I have no background in chemistry so i don't know if i'm seeing a right answer or ...
*February 4, 2015*

**Chemistry **

Once the adsorbent is packed in a liquid chromatography column, it is important that the level of the elution solvent not drop below the top of the adsorbent. Why?
*February 4, 2015*

**Chemistry **

What precautions must be taken when you introduce a mixture of compounds to be separated onto a liquid chromatography adsorbent column?
*February 4, 2015*

**Chemistry **

Once the adsorbent is packed in a liquid chromatography column, it is important that the level of the elution solvent not drop below the top of the adsorbent. Why?
*February 4, 2015*

**physics**

a metal object is suspended from a spring balance scale. the scale reads 800 N when it is suspended in air and 700 N when the object is completely submerged in water. find the buoyant force, the volume and the density of the metal.
*February 3, 2015*

**world history**

why is the ability to debate still important todat
*February 2, 2015*

**chemistry**

In 100 mL of distilled water,1.0g of thallium cholirde is added. How much of the 1.0g of TlCl doen't dissolve? The Ksp of TlCl is 3.6 x 10-6
*February 2, 2015*

**chemistry**

Please help !? Knowing that the concentration of Ag+ in a silver chromate solution is 1.5 x 10-3 M, calculate its solubility product at 25°C.
*February 2, 2015*

**chemistry**

Stuck on this one please help ! The solubility of barium sulphate, BaSO4, is 2.4 x 10-4 g/100 mL of solution. Calculate the Ksp of this solution.
*February 2, 2015*

**chemistry**

In 100 mL of distilled water,1.0g of thallium cholirde is added. How much of the 1.0g of TlCl doen't dissolve. The Ksp of TlCl is 3.6 x 10-6.
*February 1, 2015*

**chemistry**

Please help?! if 600 mL of a 0.04M KCl solution is mixed with 50mL of a 0.03M Na2SO4 solution, will a precipitate be formed? Explain your reasoning and/or show all calculations?
*February 1, 2015*

**chemistry**

I have no idea how to go about this question, please help! A clumsy chemist accidentally pours 100 mL of a 0.004 M Na2SO4 solution into a beaker containing 500 mL of 0.050 M CaCl2. Will a precipitate be formed? Explain your reasoning and/or show all calculations?
*February 1, 2015*

**chemistry**

Stuck on this questions ?! please help The solubility of barium sulphate, BaSO4, is 2.4 x 10-4 g/100 mL of solution. Calculate the Ksp of this solution.
*February 1, 2015*

**physics**

A ball is dropped from an upper floor, some unknown distance above your apartment. As you look out of your window, which is 1.5 m tall, you observe that it takes the ball 0.18 seconds to traverse the length of the window. Determine how high above the top of your window the ...
*January 30, 2015*

**AP Chemistry**

A sample of air contains 12.8 µg/m3 of beryllium dust. How many atoms of beryllium are present in a room with dimensions of 8 feet by 13 feet by 15.1 feet? Answer in units of atoms
*January 20, 2015*

**Chemistry**

You have a tank of helium with a volume of 10 liters that is currently under 40 atm of pressure. If you open the valve on the tank and release the helium into a room with a volume of 10,000 liters, how many atmospheres of pressure will the helium now be under? Second, what ...
*December 18, 2014*

**math**

A boat traveled 210 miles downstream and back. The trip downstream took 10 hours. The trip back took 70 hours. What is the speed of the boat in still water. What is the speed of the current?
*December 15, 2014*

**Math**

(13.98 + 3.96)=17.94/6=2.99
*December 12, 2014*

**Chemistry, Vapor Pressure**

Select the pair of substances in which the one with the higher vapor pressure at a given temperature is listed first. 1. C7H16, C5H12 2. CCl4, CBr4 3. H2O, H2S 4. CH3CH2OH, CH3-O-CH3 5. Xe, Kr
*December 11, 2014*

**Analytical Chemistry**

Calculate the ppm of the sodium ions when 2.91 g of sodium triphosphate are added to 2.33 L of solution. I earnestly have no idea how to solve this...
*December 9, 2014*

**Math**

) A car dealership advertises a 15% discount on all its new cars. In addition, the manufacturer offers a $1000 rebate on the purchase of a new car. Let x represent the sticker price of the car. a. Suppose only the 15% discount applies. Find a function f that models the ...
*December 4, 2014*

**ratio proportions**

The ratio of apples to oranges is 4:5. I have 200 apples and oranges total. How many are apples?
*November 18, 2014*

**math**

a basketball team needs 5 players. the team can choose from a group of 7 players. explain how to find the combinations of players that can be on the team.
*November 18, 2014*

**chemistry**

The vapor pressure of liquid chloroform, CHCl3, is 100. mm Hg at 283 K. A 0.198 g sample of liquid CHCl3 is placed in a closed, evacuated 400. mL container at a temperature of 283 K. Assuming that the temperature remains constant, will all of the liquid evaporate? What will ...
*November 11, 2014*

**Math**

A marine biologist is testing a new under water probe. The probe is catapulted from the ship into the air, descends under water to a predetermined depth, and then returns to the surface where it can be collected. The function that models the probe’s path is f(x) = 15t2...
*October 30, 2014*

**Chemistry**

what is the limiting reagent in these two reactions Reaction 1: CuSO4+2NaOH=Cuo+Na2SO4+H2O Reaction 2: CuSO4+NaCO3=CuCO3+Na2SO4
*October 22, 2014*

**Calculus**

An inverted conical tank is being filled with water, but it is discovered that it is also leaking water at the same time. The tank is 6 meters high and its diameter at the top is 4 meters. The water is being added to the tank at a constant rate. Some of this water is found to ...
*October 19, 2014*

**Calculus**

A bright light on the ground illuminates a wall 12 meters away. A man walks from the light straight toward the building at a speed of 2.3 m/s. The man is 2 meters tall. When the man is 4 meters from the building, how fast is the length of his shadow on the building decreasing?
*October 19, 2014*

**Calculus**

A pulley system on a pier is used to pull boats towards the pier for docking. Suppose that a boat is being docked and has a rope attaching the boat's bow on one end and feeding through the pier's pulley system on the other end. The pulley system is 1 meter higher than ...
*October 19, 2014*

**Check my answer?**

Conditional statement based on a Venn diagram 2 circles: large circle says quadrilaterals smaller inner circle says squares If a shape is a square then it is a quadrilateral.
*September 29, 2014*

**physics**

A ball is thrown straight upward. At 4.36 m above its launch point, the ball's speed is one-half its launch speed. What maximum height above its launch point does the ball attain?
*September 21, 2014*

**Math**

I don't know it
*September 15, 2014*

**Math**

Help please
*September 15, 2014*

**Math**

Find the distance between points (6, 16) and (–1, 14) to the nearest tenth
*September 15, 2014*

**Math**

Find the other endpoint given the first endpoint and the midpoint A = (3, 5) B = (5, -11) find C
*September 15, 2014*

**Maths**

A boy is flying a kite on a string 33m long. The string which is being held at 1.5m above the ground, makes an angle of 39* with the horizontal. How high is the kite above the ground (nearest cm)
*September 14, 2014*

**Calculus**

Suppose the area under the curve y=xe^(-mx) from 0 to 1 is 0.4. Find m.
*September 8, 2014*

**Calculus**

I am trying to find the total area under the curve, not just the integral...
*September 7, 2014*

**Calculus**

Suppose the total area under the curve y=x^2-mx+1 from 0 to 5 is 11.3024. Find m. I know that this means that i need to find the integral of the absolute value of x^2-mx+1 from 0 to 5 and set it equal to 11.3024, but I am not sure where to go from there.
*September 7, 2014*

**math**

56.67 is correct?
*September 3, 2014*

**math**

Find each unit rate. Round to the nearest hundredth if necessary. 357 miles in 6.3 hours
*September 3, 2014*