1.)Maleic acid contains 41.4% carbon, 3.47% hydrogen, and 55.1% oxygen by mass.

Question

1.)Maleic acid contains 41.4% carbon, 3.47% hydrogen, and 55.1% oxygen by mass. A 0.030-mol sample of this compound weighs 2.61 g. What is the molecular formula of maleic acid?

2.)A compound is composed of only C and F. It contains 29.65% C by mass and has a molar mass of 162.03 g/mol. What is its molecular formula?

3.)Which of the following formula/name combinations is incorrect?

HI(aq) hydroiodic acid

H2S(aq) hydrosulfuric acid

HClO3(aq) chloric acid

H2SO3(aq) sulfurous acid

H3PO3(aq) phosphoric acid

4.)How many molecules are there in 76.0 g of propylene glycol, HO(CH2)3OH?

5.How many molecules are there in 2.29 mg of mannose, C6H12O6, which is a sweet-tasting sugar that has a bitter aftertaste?

6.What is the molar mass of zinc sulfate heptahydrate, ZnSO4 ? 7H2O?

7.A certain compound has a molar mass of 90 g/mol. Which is a possible empirical formula for this compound?

9.Pure copper may be produced by the reaction of copper(I) sulfide with oxygen gas as follows:Cu2S(s) + O2(g) ? 2Cu(s) + SO2(g)What mass of copper(I) sulfide is required in order to prepare 0.500 kg of copper metal?

10.What is the percentage by mass of chlorine in DDT, C14H9Cl5?

HI(aq) hydroiodic acid

Explanation / Answer

1

Assume 100 g of sample

41.4g C---> 41.4/12= 3.45 mol

3.47g H--->3.47/1 = 3.47 mol

55.1g O---> 55.1/16= 3.44

Now, divide by the lowest 3.44

C---> 3.45 mol/3.44=1

H---> 3.47 mol/3.44=1

O---> 3.44 mol/3.44=1

The empirical formula is CHO, with mass= 29g/mol

The moleculare mass of Maleic acid is 116g/mol

then, dividing 116 by 29 (molecular formula by empirical formula) =

116/29= 4

the molecular formula is 4 times the empirical formula

4*(CHO) --> C4H4O4

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