Question

In a group assignment, students are required to fill 10 beakers with 0.720 M CaCl2. If the molar mass of CaCl2 is 110.98 g/mol and each beaker must have 250. mL of solution, what mass of CaCl2 would be used? 3.13 g 38.5 g 200 g 617 g

Answer 1

The answer is 200 g.

If the molar mass of CaCl2 is 110.98 g/mol, this means there are 110.98 g in 1 L of 1 M solution.
Let's find how many g of CaCl2 are present in 0.720 M.
110.98 g : 1 M = x : 0.720 M
x = 110.98 g * 0.720 M : 1 M 
x = 79.90 g

So there are 79.90 g in 0.720 M. In other words, in 1 L of 0.720 M solution there will be  79.90 g.

Now, we need to prepare ten beakers with 250 mL of solutions:
10 * 250 mL = 2500 mL = 2.5 L

79.90 g : 1 L = x : 2.5 L
x = 79.90 g * 2.5 L : 1 L
x = 199.75 g ≈ 200 g

Answer 2

Answer: C. 200g

Explanation: Just took the test, it's correct.