Question #ade66

1 Answer
Dec 12, 2014

The answer is 2.15g.

A solution's percent concentration by mass is defined as the mass of solute divided by the total mass of the solution and multiplied by 100%.

c=masssolutemasssolution100%

Therefore, the mass of solute needed for this solution is

mK2CO3=cmsolution100=5.00%43.0100%=2.15g

It is important to try and estimate what that mass could be even before calculating it; this could have been done by takin the 120th part (the equivalent of 5%) of 43g, which is roughly 2g.