Question

I need help on 8 can someone pls explain ?

Answer 1

So we are asked to create a solution whose volume is 500 mL and it's concentration is 1.5M. The stock solution that we can take from has a concentration of 5M.

So we can use the equation:

$M_{1}V_{1}=M_{2}V_{2}$

Where the original stock solution will be the '1' subscripts and the new solution will be the '2' subscripts. It is important to note here that volume in this equation is in L, not mL. So we must do the conversion (1,000 mL = 1 L). So let's plug this in and solve for the amount of stock that we should take:

$(5M)(V_{1})=(1.5M)(0.5L)$

$V_{1}=0.15L$

So therefore we must take 150 mL of the original 5M stock solution to put into the new 1.5M glucose solution. To make the total equal 500 mL, we must then use deionized water to make up the rest of this solution, so we would need the remaining 350 mL to be water.