Homework Help: Chemistry

Posted by Shelly on Tuesday, November 29, 2011 at 9:24pm.

At 20 degrees C ethanol has a density of 0.789 g/ml and H2O has a density of 1.0 g/ml. What is the % by volume of ethanol of a solution made by adding 50g of ethanol with 50g of H2O?

Tutor Answer: Use density = mass x volume to convert 50 g ethanol to volume and to convert 50.0 g H2O to volume.
%ethanol v/v = (volume ethanol/total volume?)*100 = ?

MY QUESTION:
i thought that density = m/v

i've done the math and i think you are right because based on the above formula my answer is 126.74%
However, i don't understand why if the density formula is as you stated?

2nd, is this correct?

1/50 = .02, 1/.789 = .01578

(0.01578/0.02) x 100 = 78.9%

Chemistry - DrBob222, Wednesday, November 30, 2011 at 12:19am
Yes, you are right about density and no, I don't get those answers. For that density sentence I punched x instead of / button. density = mass/volume and
volume = mass/density.
50 g ethanol has v = 50/0.789 or about 60 mL (but you need to do it more accurately). Water has volume of 50/1 = 50 mL . Total 50 + 60 = 110 and percent ethanol = (volume ethanol/total volume) x 100 which is approximately 55%.
1/50 = 0.02 but
1/0.789 is not what you wrote.
Chemistry - Shelly, Thursday, December 1, 2011 at 10:28am
Thank you for your help!

Answer this Question

Related Questions

Chemistry - At 20 degrees C ethanol has a density of 0.789 g/ml and H2O has a ...
chemistry - What is the mass/vol % ethanol in an ethanol-water solution with ...
Chemistry - 25.0 mL of ethanol (density = 0.789 g/mL) initially at 7.0 degrees ...
Chemistry - You dissolve 20.0 gms of sucrose (sugar) in 200 mL of ethanol 20&...
math - what is the mass of 1.00 L of ethanol? Ethanol has a density of 0.798 g/...
Chemistry I - 25.0 mL of ethanol (density = 0.789 g/mL) initially at 4.2°C ...
science - what is the mass of a 257 mL sample of ethanol (ethyl alcohol) at 20 ...
Chemistry - At room temperature, ethanol's density is 0.789 g/mL while water...
chemistry - Listerine mouthwash is 21.6%ethyl alcohol by volume. What mass of ...
Chemistry - Listerine mouthwash has 21.6% ethyl alcohol by volume. What mass of ...

For Further Reading

First Name:
School Subject:
Answer: