Help in chemistry! mass % problem to solve?

Question

What mass of solute, in grams, is required to prepare 150.0 grams of a 2.50 % (by mass) aqueous solution of KCl?

Answer 1

1) To prepare this solution you should do:

100 g of solution needs 2.5 g of solute (to get 2.5% mass/mass)
150 g of solution needs x g of solute (to get 2.5% mass/mass)

2) x = (150 g x 2.5 g / 100 g) = 3.75 grames of KCl

That's it!

Good luck!

Answer 2

in the beginning you're able to discover what proportion moles of Mg(OH)2 there are. The molar mass of Mg(OH)2 in accordance on your numbers could be 24.31 + 2 x sixteen.00 + 2 x a million.01 = fifty 8.33 g/mol consequently, the style of moles you have of Mg(OH)2 = ninety seven.4g/fifty 8.33g/mol = a million.sixty seven mol Now all of us be responsive to that for each Mg(OH)2, we've one Mg, and a pair of O's and 2H's If we've a million.sixty seven moles of Mg(OH)2, we've a million.sixty seven moles of Mg because of the fact the molar mass of Mg = 24.31g/mol, we are able to do a million.sixty seven mol * 24.31g/mol and we get 40.60 grams of Mg