An aqueous salt solution is 15.0% mass sodium chloride. How many grams of salt are in 250.0 grams of this solution? Use correct significant figures.

37.5 g NaCl

Explanation:

Step 1: Given data

Step 2: Calculate how many grams of NaCl are in 250.0 g of solution

The concentration of NaCl is 15.0% by mass, that is, there are 15.0 g of NaCl every 100 g of solution.

250.0 g Solution × 15.0 g NaCl/100 g Solution = 37.5 g NaCl

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g

1. they vary with a higher number because boiling is way hotter than melting