Question

For an experiment, a biology student makes 1 liter of a solution containing the substances shown in the table below. Using the given information, fill in the missing parts of the table for each substance by (a) providing the formula weight and (b) calculating either the mass the student needs to weigh out or the number of moles that the student has, based on the amount weighed out. For each calculation, show your work? Be sure to include the formula mass of water for CaCl2 • 2H2O and Na(CH3)2 AsO2 • 3H2O.

Answer 1

To calculate the missing parts of the table, determine the formula weight and either the mass or number of moles. For CaCl2 • 2H2O, the formula weight is 111.43 g/mol and 2H2O is 36.03 g/mol. For Na(CH3)2AsO2 • 3H2O, the formula weight is 183.91 g/mol and 3H2O is 54.03 g/mol.

Step-by-step explanation:

In order to calculate the missing parts of the table for each substance, we need to determine the formula weight and either the mass or number of moles. Let's start with the first substance, CaCl2 • 2H2O, which is calcium chloride dihydrate. The formula weight can be calculated by adding the atomic weights of the elements in the compound:
CaCl2 = 40.08 (calcium) + 2(35.45) (chlorine) = 111.43 g/mol, and 2H2O = 2(1.01) (hydrogen) + 2(16.00) (oxygen) = 36.03 g/mol.

For the second substance, Na(CH3)2 AsO2 • 3H2O, which is sodium dimethylarsinate trihydrate, the formula weight is calculated as follows: Na(CH3)2AsO2 = 22.99 (sodium) + 2(12.01) (carbon) + 6(1.01) (hydrogen) + 75.95 (arsenic) + 32.00 (oxygen) = 183.91 g/mol, and 3H2O = 3(1.01) (hydrogen) + 3(16.00) (oxygen) = 54.03 g/mol.

Using this information, you can now fill in the missing parts of the table for each substance by calculating either the mass or number of moles based on the amount weighed out.