Question

heptane and water do not mix, and heptane has a lower density (0.684g/mL) than water (1.00g/mL). A 100mL graduate cylinder with an inside diameter of 3.10 cm contains 39.90g of heptane and 34.00g of water. What is the combined height of the two liquid layers in the cylindar?

I figure out that the heptane is 39.90/0.684=58.3ml
water is 34.00/1=34.00ml

I know the diameter is 3.10cm and to get the radius I divide 3.10/2=1.55 and then I raise it by 2 which it 2.4025cm^2.

I don't know to get the rest

Answer 1

Wouldn't it be done this way?
pi*r^2*h = volume.
You know pi and r and you know the volume is 58.333+34.000 =- ? so solve for height. Then round to 4 significant figures. (Note: Since you know grams to 4 s.f., I would not round to 58.3 but keep it at 58.333 and round at the end.)