of impure calcium carbonate is added to of HCl (in excess). The leftover acid needs of NaOH. Assuming the impurities do not react, what is the percentage purity of the sample? ( .)
Answer and explanation
Correct answer: D.
- Step 1: Total HCl mol. Excess HCl mol.
- Step 2: HCl reacted mol. means mol of .
- Step 3: Mass g, so purity .
Answer
.
Why not the others: : treats the moles of HCl reacted as the moles of , ignoring the ratio. : assumes all the HCl added reacted with the carbonate. : uses the moles of excess acid for the carbonate.
Practise more Quantitative chemistry.
Free questions with an explanation for every one, and full timed ESAT (Engineering and Science Admissions Test) mock tests.
More Quantitative chemistry questions
- What mass of calcium carbonate, , is mol? (: Ca , C , O .)
- of sodium chloride () is dissolved to make of solution. What is the concentration?
- A compound contains carbon, hydrogen and oxygen by mass. What is its empirical formula? (: C , H , O…
- What is the atom economy for making calcium oxide by heating calcium carbonate: ? (…
- What is the percentage by mass of nitrogen in ammonium sulfate, ? (: N , H , S , O .)
- of methane burns completely in oxygen: (steam). What vo…