Friday

January 20, 2017
Total # Posts: 159

**Math**

I am still confused! Equation: C1V1=C2V2 Given: C1= 15 mM V1=? C2= 0.25 mM V2= 1mL (Do I just plug 1mL into the equation or do I have to convert to liter? Does mM mean mmol/1L?) I got ~17 microliter. Note: I must convert my answer to microliter. Math - bobpursley, Saturday, ...

*January 15, 2017*

**Math**

Equation: C1V1=C2V2 Given: C1= 15 mM V1=? C2= 0.25 mM V2= 1mL (Do I just plug 1mL into the equation or do I have to convert to liter? Does mM mean mmol/1L?) I got ~17 microliter. Note: I must convert my answer to microliter.

*January 14, 2017*

**Math- Reply to bobpursely**

I need to convert my answer (volume) into microliter.

*January 14, 2017*

**Math**

Calculate the amount of fluorescein (MW 332.31) you will need to make 10 mL of 15 mM solution in ethanol (EtOH). My answer:0.05 g 2.Using Equation C1V1=C2V2 calculate the volume of stock solution (15 mM) you need to make 1 mL of each working solution concentration: 0 mM and 0....

*January 14, 2017*

**Math**

1. Calculate the amount of fluorescein (MW 332.31) you will need to make 10 mL of 15 mM solution in ethanol (EtOH). My answer:0.05 g 2.Using Equation C1V1=C2V2 calculate the volume of stock solution (15 mM) you need to make 1 mL of each working solution concentration: 0 mM and...

*January 14, 2017*

**Math**

If it is 4:00 p.m. then what time is 17 hours ago? Is it 11:00 pm?

*January 5, 2017*

**Physics**

A ceiling fan draws a current of 0.625 A and has a voltage of 120 V. The resistance of the ceiling fan, to the nearest tenth?

*November 16, 2016*

**Math**

Thank you!

*November 8, 2016*

**Math**

Are you able to show me the work to get this answer? I'm not able to get the same answer. I'm coming up with 0.3782. Thank you.

*November 8, 2016*

**Math**

A 9.2 ounce can of tomato juice costs $3.48. What is the price per ounce of the tomato juice to the nearest cent?

*November 8, 2016*

**Math**

30 miles/2.5 hours = 12 miles/hour 12 miles/hour * 4.5 hours = 54 miles

*October 11, 2016*

**6 grade math**

Density is equal to mass divided by volume. To find volume, multiply the length, width, and height. This applies for any rectangular prism. In the case of a cube, all sides are the same, so multiply 2*2*2 or 2^3. You'll get 8 cm^3. D = m/V, so D = 32/8 = 4 g/cm^3. :)

*October 11, 2016*

**Chemistry**

To clarify, a triple bond between carbon and oxygen is more stable than a triple bond between carbon and nitrogen because oxygen is more electronegative. Is my understanding correct?

*September 30, 2016*

**math**

7+6-12=13-12=13(+)-12=1

*September 29, 2016*

**Grammar**

Which is correct? I think the second one is correct. 1. Thank you John, Peter, Susan, and Veronica to be a part of the crew. OR 2. Thank you John, Peter, Susan, and Veronica for being a part of the crew.

*September 23, 2016*

**Economics**

I think 5 would be A because an external cost will affect a third party, so someone else than who made the decision in the first place.

*July 5, 2016*

**physics**

Four copper wires of equal length are connected in series. Their cross-sectional areas are 0.96 cm^2, 2.02 cm^2, 2.90 cm^2, and 5.06 cm^2. A potential difference of 116 V is applied across the combination. Determine the voltage across the 2.02 cm^2 wire.

*May 25, 2016*

**Algebra**

A box contains 5 yellow balls, 3 blue, and 1 red ball. Two balls are drawn at random. Find the probability that the two balls are yellow

*May 22, 2016*

**Algebra**

Write each series as a summation in sigma notation. (−1)^2+0^2+1^2+2^2+3^2

*May 15, 2016*

**Algebra**

Write each series as a summation in sigma notation. 5+8+11+14 i=1

*May 15, 2016*

**Life Orientation**

Discriminations

*April 10, 2016*

**Algebra**

Give the list of elements and write in the form with condition the following sets: the set of natural numbers that are multiples of 3

*April 3, 2016*

**Adv. Func./Science Question**

Hi, I have this question that I will be tested on but my teacher didn't teach us how to do it so I am confused on how to even start. Please explain on how to start the question...thank you How bright a star appears can depend on how much light the star actually emits and ...

*December 12, 2015*

**Math**

See what 12 and 9 go into (3) 3 goes into 12 4 times 3 goes into 9 3 times take the biggest number and times both of them by that number. 9x4 = 36 12x4 = 48 Take the number 3 goes into and add that number to 9:15am 3:30

*September 27, 2015*

**gravimertic prob**

an organic pesticide (mw 183.7) is 8.43% cl. a 0.627g sample containing the pesticide plus inert material containing no chloride was decomposed with metallic sodium in alcohol. the liberated chloride ion was precipitated as agcl weighing 0.0831g. calculate the percentage of ...

*April 26, 2015*

**gravimetric**

in the gravimetric determination of barium in BaCrO4, what weight of sample must be taken so that the weight of the precipitate in milligrams multiplied by 100 will equal the % Ba in the sample?

*April 20, 2015*

**gravimetric prob**

689.64 mg is the new ppt? am i right?

*April 20, 2015*

**gravimetric prob**

A sample of freshly precipitated silver chloride weighs 704.7mg. Before the solution can be filtered and washed 10.0mg of AgCl is photodecomposed. After the precipitate is filtered and washed another 10.0 mg of AgCl is photodecomposed. Calculate the weight of the precipitate.

*April 20, 2015*

**gravimetric prob**

Difference between initial and final perchlorate(18.6137-18.6448) = 0.0311 ascarite(16.8425-16.9098)= 0.0673 %H= (0.0311x2x1.00784/44.00766)/947.4×100= 0.000150355 %C=(0.0673x12.0096/44.0076)/947.4x100=0.001938572 0.000150355x1mol/1.00784= 0.000148866 0.001938572x1mol/12...

*April 20, 2015*

**gravimetric prob**

A pure organic compound weighing 947.4mg was heated in a stream of oxygen. The effluent gas was swept successively through a tube of magnesium perchlorate dessicant weighing 18.6137g and a tube of Ascarite weighing 16.8425g. After several minutes the tubes were sealed and ...

*April 20, 2015*

**Further maths**

Two functions f and g are defined over the set of R of real numbers as follows: f:x=2x-3 g:x=xsquare+5 find f[g(x-1)]

*April 18, 2015*

**Chemistry**

How much energy in joules is required to heat 25g of ice from -10.0 C to 0.0C and change it to water. The specific heat is 2.09J Please explain

*April 16, 2015*

**Phsyics HELP!**

A car accelerates uniformly from +10.0 m/s to +50.0 m/s over a distance of 225 m. How long did it take to go that distance? Show all your work, including the equation used, given and unknown quantities, and any algebra required. Make sure your answer has the correct number of ...

*March 5, 2015*

**Physics**

A plane traveling at 200.0 km/h attempts to land on a 250 m runway. The plane’s engines and brakes accelerate uniformly at –7.0 m/s2. Will the plane be able to land safely? Show all your work. Include any equations used, including the given and the unknown. Show all ...

*March 5, 2015*

**life orientation**

Life orientation

*February 18, 2015*

**math**

In Carl's drawer, he has white,gray,and black socks. In his closet,he has black brown,and blue shoes. I need to make a diagrdiagram to display the sample space for Carl choosing a sock and shoe color. Is this right White/black,brown blue Gray/black,brown,blue Black/black ...

*January 21, 2015*

**physics**

a man steps out of a rowboat into a dock. The man has a mass of 80 kg and moves forward with a velocity of 1.5 m/s. If the boat has a mass of 120 kg. and was initially at rest, what is its final velocity?

*November 26, 2014*

**math**

1. He wants 1/2 pound of chicken so one complete serving. The remainder is 1/4, half of a half is one fourth so the answer is 1 and a half servings. 2. (n ×3/2) ×2 n being the original amount the recipe calls for 3. Use the formula to solve 4.yes oregano, no for ...

*October 27, 2014*

**Chemistry**

Construct a cycle with the following steps: Begin with: 1 mol ideal monatomic gas at 300 K and 1 bar. Point A. 1. Isothermal reversible expansion till volume gets twice its original value. Point B. then, 2. Irreversible adiabatic expansion against P_ext=0.25 bar till P_ext=...

*October 6, 2014*

**Chemistry**

During recrystallization, an orange solution of a compound in hot alcohol was treated with activated carbon and then filtered through fluted paper. On cooling, the filtrate gave gray crystals, although the compound was reported to be colorless. Explain why the crystals were ...

*September 28, 2014*

**Physics**

A ball is thrown at 41° below the horizontal from a rooftop of height 65 m. It lands 2 s later. Find: Find: a) its initial speed b) the point of impact with the ground; m from the base of the building c) the angle at which it hits the ground. ° below the horizontal

*September 28, 2014*

**physics**

A ball is thrown horizontally at 15 m/s from a clifftop 60 m above the sea level. Find: a) the time to land; b) the angle at which it hits the water; ° below the horizontal c) the speed at which it hits the water. m/s

*September 28, 2014*

**Physics**

An electron in an atom has a speed of 2.2 × 10^6 m/s and orbits the nucleus at a distance of 5 × 10^-11m.a)What is its centripetal acceleration? b)A neutron star of radius 17 km is found to rotate at 5 revolutions per second. What is the centripetal acceleration of...

*September 28, 2014*

**math**

I don't know

*September 25, 2014*

**math**

What is the smallest six digit number you can make that would round to 126000?

*September 4, 2014*

**soc 313**

ella miller and her family issues

*May 19, 2014*

**math**

in an album, the ratio of the number of local stamps to the number of foreign stamps was 7 : 4. When Lucy gave away 8 local stamps and 8 foreign stamps, there were 1.8 as many local stamps as foreign stamps in the album. find the total number of stamps Lucy had in the end.

*March 5, 2014*

**Math**

Two fishing boats depart a harbor at the same time, one traveling east, the other south. The eastbound boat travels at a speed 7 mi/h faster than the southbound boat. After seven hours the boats are 91 mi apart. Find the speed of the southbound boat.

*January 23, 2014*

**physics**

sin 27=0.45=59/x => x=115.69 tan27=0.51=59/y => y=131.11 ratio=y/x => ratio= 1.1

*November 25, 2013*

**9th grade Geography**

what shape describes the united states

*August 21, 2013*

**Math**

lee and his family are planning a hiking trip on the Appalachian trail. they are packing food in 2lb bundles. how many bundles can they make with 36 lb of food? write a number sentence to help you solve this problem.

*May 20, 2013*

**college algebra**

i need help with elimination and substitution linear equation

*May 5, 2013*

**Math**

Jimmy is rolling a number cube labeled 1-6 and also spinning a 3-section spinner labeled red, yellow, and blue. How many outcomes are possible What are they? make a list what is the probability of spinning yellow? 4. If Mary says she always rolls yellow with even numbers 80% ...

*April 22, 2013*

**Science (chemistry)**

Pls help.. Q: prepare a table of value for acid-base titration using 26.40cm^3 as end point

*March 15, 2013*

**Chemistry**

Two liquids A and B have vapor pressures of 71.3 and 131 mmHg, respectively, at 25 degrees Celsius. What is the total vapor pressure of the ideal solution made up in the following concentrations? 1.00 mole of A and 1.00 mole of B 2.00 moles of A and 5.00 moles of B

*December 7, 2012*

**singapore moth**

first row- 9,3,1 second row- 4,7,2 first colum- 1,8,4 second column-2,6,5

*November 4, 2012*

**Algebra**

if a ball standing on four legs wetght 1,200 pounds,how much will this bull weigh when standing on three legs

*August 23, 2012*

**Hypothesis - Statistics**

At one school, the average amount of time that tenth-graders spend watching television each week is 18.4 hours. The principal introduces a campaign to encourage the students to watch less television. One year later, the principal wants to perform a hypothesis test to determine...

*July 28, 2012*

**math**

A researcher wishes to estimate the proportion of college students who cheat on exams. A poll of 490 college students showed that 33% of them had, or intended to, cheat on examinations. Find the margin of error for the 95% confidence interval.

*July 15, 2012*

**math**

A government survey conducted to estimate the mean price of houses in a metropolitan area is designed to have a margin of error of $10,000. Pilot studies suggest that the population standard deviation is $70,000. Estimate the minimum sample size needed to estimate the ...

*July 15, 2012*

**programming in c++**

a program in c++ that accepts exam marks for 10 students and stores them in an array.the program should then calculate and utput the average marks for the class.and give an account of marks below average and output all marks above average.

*June 19, 2012*

**chemistry**

A mixture of 16 g of salt and 47 g of baking soda is poured into 296 ml of water. What is the total mass of the mixture in grams?

*June 14, 2012*

**Geometry**

If the two lines are perpendicular, what is x + y 2y- 10 2x+1

*May 22, 2012*

**chemistry**

Calculate the theoretical pH when 5.00 ml of 0.0100 M HCl is added to 30.00 mL of deionized water.

*April 29, 2012*

**math**

explain how to compare 0.34 and 0.27

*April 26, 2012*

**math**

Mia is stacking copies of a new book in a square-pyramid display by the front window of her bookstore. for each consecutive layer, she places one book where four meet. A. I the bottom row of the display has 144 books and there is one book on the top, determine how many rows of...

*March 14, 2012*

**statistics**

-2.262

*March 4, 2012*

**Calculus 2**

how do we know if the curve theta = pi/2 is a circle, or semicircle, or spiral? I've tried to change the curve to x and y, but both sides of the equation are the same, and tan(pi/2)=infinity.

*February 28, 2012*

**chemistry**

2 solutions of equal amounts in a u-tube are separated by a semipermeable membrane. The level os the (more/less( concentrated will rise. I think the answer is (more) but I'm not sure. What do you think?

*February 9, 2012*

**Chemistry**

Which of the following solutions will have a higher boiling point? A. 1m C6H12O6 B. 1m NaCl C. 1m MgCl2 D. 1m AlCl3 And pls explain why it is. Thank you so much!!

*February 9, 2012*

**Calculus**

∫[(x+3)/(x^2 +9)]=????? Can you give me a hint for solving it?

*February 8, 2012*

**chemistry**

The freezing-point depression is -0.930 Celsius degree. Determine the molality of the solution of an unknown nonelectrolyte in water. Please help!! I do not understand this problem!

*February 7, 2012*

**arithmetic**

The first three terms in an arithmetic are given by x,4x+5 and 10x-5.find the value of x.

*January 21, 2012*

**Gravi prob chem**

in the gravimetric determination of barium in BaCrO4, what weight of sample must be taken so that the weight of the precipitate in milligrams multiplied by 100 will equal the % Ba in the sample?

*January 16, 2012*

**organic chemistry--please help me!!!**

Give equations to show how sulfuric acid can convert 4-methylcyclohexene into a mixture of four isomeric c7H12 compounds(including starting material). Predict the relative amounts of each isomer.

*October 31, 2011*

**Maths**

Calculate the volume and curved surface area of a cone 14cm in base diameter and 24cm high

*October 26, 2011*

**Maths**

A right pyramid on a base 4cm square has a slant edge of 6cm.calculate the volume of the pyramid

*October 26, 2011*

**organic chemistry --please help me!!!!!!!!!!!!!!!**

Calculate the theoretical yield for the bromination of bothstilbenes and cinnamic acid, assuming the presence of excesspyridinium tribromide. cinnamic acid - 150 mg cis-stilbene - 100 μL trans- stilbene - 100 mg pyridinium tribromide - 200-385 mg

*October 20, 2011*

**organic chem**

How do injector temperature and detector temperature affect retention time of a compound in gas chromatography?

*October 7, 2011*

**organic chem**

An unknown compound melted at 131-133°C. It is thought to be one of the following compounds(mp,°C): trans-cinnamic acid (133-134); benzamide(128-130); DL-malic acid(131-133); or benzoin(135-137). The mixture melting points of the unknown compound with each of the test ...

*September 8, 2011*

**organic chem**

in simple distillation or fractional distillation do the changes in temperature occur more gradually? and why?

*September 6, 2011*

**organic chem**

why should we notify the laboratory instructor of any incidents that occur in laboratory?

*September 1, 2011*

**organic chem**

what steps should we do if a large bottle of acetone is broken and spilled in the laboratory?

*September 1, 2011*

**organic chem**

what steps should we do if ethanol in a beaker ignites in the laboratory?

*September 1, 2011*

**Business Math**

Earl wants to retire to San Diego when he is 65, he is now 50. He will need $300,000.00, how much would he have to invest today @6% interest compounded semiannually to meet his goal?

*May 18, 2011*

**business math**

Greg will need $218,000.00 in 15yrs for college bills, how much does he have to invest today @8% compounded semiannually?

*May 18, 2011*

**chemistry**

i checked through my work and I found out i didn't do square root for the x^2....thats why my answer was double 6.011.

*May 15, 2011*

**chemistry**

i worked through it just don't know it i did it right...

*May 15, 2011*

**chemistry**

Calculate the pH at the equivalence point for the titration of a solution containing 1250.0 mg of hilariamine (MW = 92.5 g/mol, Kb = 8.1×10−4) with 0.1000 M HCl solution. The volume of the solution at the equivalence point is 175.0 mL. (I got the answer to be 12....

*May 15, 2011*

**chemistry**

Calculate the pH at the equivalence point for the titration of a solution containing 1250.0 mg of hilariamine (MW = 92.5 g/mol, Kb = 8.1×10−4) with 0.1000 M HCl solution. The volume of the solution at the equivalence point is 175.0 mL. (I got the answer to be 12....

*May 15, 2011*

**chemistry**

i got 11.5 but im not sure because the problems i did before i had to change to ka first and that was the pH and got those answers right...but i don't understand why i have to do it this way though its the right way...quest is saying its wrong..

*May 13, 2011*

**chemistry**

What would be the pH of a 0.563 M solution of ammonia (NH3) at room temperature? The Kb of ammonia is 1.78 × 10−5. 1. 2.5 2. 7 3. 9 4. 4.5 5. 11.5 ( I did this problem but apparently 4.5 isnt the answer)

*May 13, 2011*

**chemistry**

What would be the pH of a 0.563 M solution of ammonia (NH3) at room temperature? The Kb of ammonia is 1.78 × 10−5. 1. 2.5 2. 7 3. 9 4. 4.5 5. 11.5 ( I did this problem but apparently 4.5 isnt the answer)

*May 13, 2011*

**chemistry**

Consider the ionization constants hypochlorous acid (HOCl) : Ka = 3.5 × 10−8; ammonia (NH3) : Kb = 1.8×10−5. A solution of ammonium hypochlorite (NH4OCl) is 1. acidic, because the cation hydrolyzes to a greater extent than the anion. 2. basic, because ...

*May 13, 2011*

**chemistry**

The problem didn't include Ka

*May 12, 2011*

**chemistry**

i did it and used 6.2E-10. my answer wasn't there so i was wondering if i did something wrong..i got 7.11 for pH

*May 12, 2011*

**chemistry**

What is the pH of 8.94 × 10−6 M HCN(aq), ignoring the effect of the autoprotolysis of water? 1. 7.17923 (basic; thus not reasonable) 2. 6.03594 3. 7.30027 (basic; thus not reasonable) 4. 5.50032 5. 7.38101 (basic; thus not reasonable) 6. 5.18207 7. None of these

*May 12, 2011*

**chemistry**

Calculate the pH of the solute in an aqueous solution of 0.0047 M codeine, if the pKa of itsconjugate acid is 8.21. What is the percentage protonation of the solute?

*May 12, 2011*

**chemistry(Acid&Base)**

is the answer 2)5.3....

*May 12, 2011*

**chemistry(Acid&Base)**

Calculate the solubility product of calcium hydroxide if the solubility of Ca(OH)2(s) in water at 25◦C is 0.011 M. Choices: 1. 1.1 × 10−5 2. 5.3 × 10−6 3. 2.7 × 10−6 4. 1.5 × 10−8 5. 1.2 × 10−4

*May 12, 2011*