To identify a liquid substance, a student determined its density. Using a gradua

Question

To identify a liquid substance, a student determined its density. Using a graduated cylinder, she measured out a 45-mL sample of the substance. She then measured the mass of the sample, finding that it weighed 38.5 g. She knew that the substance had to be either isopropyl alcohol (density 0.785 g/mL ) or toluene (density 0.866 g/mL ).

An experiment requires 53.5 g of ethylene glycol, a liquid whose density is 1.114 g/mL. Rather than weigh the sample on a balance, a chemist chooses to dispense the liquid using a graduated cylinder. What volume of the liquid should he use?

A cubic piece of metal measures 3.50 cm on each edge. If the metal is nickel, whose density is 8.90 g/cm3, what is the mass of the cube?

Explanation / Answer

Q1. To identify a liquid substance, a student determined its density. Using a graduated cylinder, she measured out a 45-mL sample of the substance. She then measured the mass of the sample, finding that it weighed 38.5 g. She knew that the substance had to be either isopropyl alcohol (density 0.785 g/mL ) or toluene (density 0.866 g/mL ).

mass = 38.5 g ;

Volume = 45 mL

Density = mass/Volume = 38.5/45 = 0.85555 g/mL

nearest value is Toluene's density.

therefore it must be toluene

Q2. An experiment requires 53.5 g of ethylene glycol, a liquid whose density is 1.114 g/mL. Rather than weigh the sample on a balance, a chemist chooses to dispense the liquid using a graduated cylinder. What volume of the liquid should he use?

Apply Density equation

Density = mass / volume

solve for volume

volume = mass/density = 53.5g / 1.114g/mL = 48.025 mL

V = 48.025 mL

Q3. A cubic piece of metal measures 3.50 cm on each edge. If the metal is nickel, whose density is 8.90 g/cm3, what is the mass of the cube?

If this is a cube, then

Volume = L^3 = (3.5 cm) ^3 = 42.875 cm3

D = 8.0 g/cm3

mass = D*V = (8 g/cm3 ) (42.875 cm3) = 343 g of metal

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