How many grams of KHP (HC8H4O4K) are needed to make 250.00 mL of a 0.100 M solution? To calculate how many grams of KHP are needed, it is first necessary to calculate the number of moles of KHP in 250.00mL of 0.100 M solution. Once this is done, the moles can be converted to grams by using the molecular weight of KHP (HC8H4O4K). Show method of calculations.