Question

Calculate the mass of K2CRO4 needed to make 3.00 L of a 0.0200 M solution.

Answer 1

First we get the molar mass of K2CrO4. To get the molar mass, just get a periodic table, find the individual masses of the elements and add them all based on the chemical formula. Thus,
K2CrO4: 2*39.1 + 1*52 + 4*16 = 194.2 g/mol
Then recall that molarity is equal to moles of solute per liter of solution, or
M = n/V
Substitute the given values to get n:
0.02 = n / 3
n = 0.06 mol K2CrO4
Finally, multiply this by the molar mass:
0.06 * 194.2 = 11.7 g K2CrO4

Hope this helps~ :3

Answer 2

Thank you!!!!!!!!! :)