Density and Percent Calculations

Chemistry                                                                                                                                                         GIA 5-4
Unit 5: Chemical Quantities and Calculations                                                                                         Reading: Chapter 3

Learning Objective:  To understand how to use density and percent as ratio to solve problems.

Working Mode: Pairs   

1.  A square container has 10.0 cm sides.  Calculate the mass (g) of carbon tetrachloride (CCl₄  molar mass 153.8 g) that must be added to the container to obtain to fill the container to a height of the 30.0 cm.  The density of carbon tetrachloride is 1.594 g/mL. (1 cm³ = 1 mL) Consider the number of significant figures the answer should have.

Step 1: Determine the volume that carbon tetrachloride occupies in the container. 

Step 2: Determine the mass (g) of carbon tetrachloride in the container. 

2.  What is the volume in mL of one metric tonne of gold (1000 kg = 1 metric tonne), if the density of gold is 19.3 g/mL?

3.  A mixture of liquid carbon disulfide (CS₂  molar mass 76.13 g) and liquid benzene (C₆H₆  molar mass 78.11g) that had a mass of 64.0g was found to be 45.0 % carbon disulfide by mass.  The density of carbon disulfide is 1.263 g/mL and the density of benzene is 0.879 g/mL.  Calculate the volumes of carbon disulfide and benzene that were added together to form the mixture.

Step 1: Find the mass of carbon disulfide in the mixture.

Step 2: Find the mass of benzene.  

Step 3: Find the volume of benzene.

Step 4: Find the volume of carbon disulfide.                  

4.  A hospital patient needs a saline intravenous solution (IV).  Saline IVs typically contain 5% NaCl in water.  How many grams of NaCl must the lab technician add to 25 L of water to make a 5% NaCl IV solution?  (1 L = 1000 mL; water’s density is 1g/mL)