Question

Calculate the amount in grams of solid K2CrO4 to make 100ml of a0.2 M aqueous solution of K2CrO4.(Please explain SF)

Answer 1

The first step is to convert the volume of solution in mililiters to liters, use a conversion factor to do it:

`100mL\cdot(1L)/(1000mL)=0.1mL`

Now, multiply the volume of the solution by its concentration to find the number of moles that are needed to make that solution (remember that M=mol/L):

`0.1L\cdot(0.2mol)/(L)=0.02mol`

Finally, convert this amount of moles to grams using the molecular weight of K2CrO4 (MW=194.2g/mol):

`0.02mol\cdot(194.2g)/(mol)=3.884g`

The amount of grams of K2CrO4 to make 100ml of solution is 3.884g.