How many grams of KF do you need to weigh in order to prepare 500. mL of solution with a concentration of 0.250 M?

Answer 1

M = mols/L and rearrange to mols = MxL
and mols = grams/molar mass
Therefore, since mols = mols we can set those equal to each other to obtain
mols = M x L = mols = grams/molar mass and
L x M x molar mass = grams.
Plug in the numbers and solve for grams.

Answer 2

I'm sorry, I don't even know where I should start plugging in. I got lost when you rearranged to mols = MxL.

Answer 3

M=mol/L

L*M = mols

just multiply both sides by L

Answer 4

Just use what I ended up with; i.e.,
M x L x molar mass = grams.
You have M, L, and molar mass. Solve for grams.

Answer 5

Okay...

M x L x mm = grams

0.250 M x 0.5 L x 57.9g = 7.24 grams

Answer 6

math looks fine but as for significant figures I'm not so sure.

Answer 7

Is that it for the problem, or is there another step I have to do?

Answer 8

That is the answer for the problem but as for significant figures it just means how many numbers you show for the answer.

for example if your answer is 8.93383494 right ? but the initial numbers given is 33.28 and 8.9 and because the 8.9 has the least significant figures (2) vs the 33.28's (4), then the answer would be 8.9.

Answer 9

So 7.2 g would be correct then?