You have 2.0 g of solid A, 100.00 mL of water (100.0 g of water), and the total mass of solid A combined with 100.00 mL of water is found to be 102.0 g. The mass percent of A in this solution is
Mass percent is defined as # grams solute per 100 g solution and that times 100.
So you have 2 g solute and 102 g of solution. Ergo!
@ DrBob222, i tried your way already and it didn't work.
2/102 x100=1.96 can you double check again
You have done it correctly. What you may not have done (especially if you are checking your answer through a data base AND if your prof is picky about significant digits) is to round.
(2.0/102.0)*100 = 1.96078, which to two s.f. (all you are allowed with the 2.0 value) rounds to 2.0%
To find the mass percent of A in the solution, you first need to determine the mass of A in the solution.
To do this, subtract the mass of water from the total mass of the solution.
Total mass of the solution = mass of solid A + mass of water
Mass of solid A = Total mass of the solution - mass of water
Mass of solid A = 102.0 g - 100.0 g = 2.0 g
Now that you have the mass of solid A in the solution, you can calculate the mass percent.
Mass percent = (Mass of A / Total mass of solution) x 100
Mass percent = (2.0 g / 102.0 g) x 100 = 1.96%
Therefore, the mass percent of A in this solution is 1.96%.