Question

5.etermine the mass of titanium in 57.2 g of titanium(IV) oxide. The mass percent of
titanium in titanium(IV) oxide is 59.9%.

6. Calculate the mass percent composition of potassium in potassium oxide (K2O)

7. A laboratory analysis of vanillin, the flavoring agent in vanilla, determined the mass
percent composition: C, 63.15%; H, 5.30%; O, 31.55%. Determine the empirical
formula of vanillin.

8.Acetylene, a gas often used in welding torches, has the empirical formula CH and a
molar mass of 26.04 g/mol. Find its molecular formula.

9. If a woman consumes 22 g of sodium chloride, how much sodium does she
consume?
Sodium chloride is 39% sodium by mass.

Answer 1

5)

% mass of Titanium in titanium(iv)oxide =59.9

So, mass of Titanium in 100 g of titanium(iv)oxide =59.9 g

mass of Titanium in 57.2 g of of Titanium(iv) oxide =

= 34.26 g

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6)

Molar mass of K2O = 94.2g/mol

Atomic mass of K = 39.09 g/mol

So 94.2 g of K2O contains 39.09 g of potassium

Mass of potassium in 100 g of K2O =

= 41.5 g

So percent composition of potassiun in K2O = 41.5% by mass

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7)

The percent is taken number of grams of each element present per 100 g of the compound.

Element	% of element	# moles based on % given(percent/At.mass)	simple ratio (as whole numbers)	Final simple ratio
C	63.15		=2.7	8.1
H	5.30		=2.7	8.1
O	31.55		= 1	3

So the simple ratio of moles of atoms C: H: O = 8.1: 8.1: 3

The above ratio can be rounded off to nearest as C: H: O = 8: 8: 3

The empirical formula of vanillin=

Note -------- if the simple ratio is multiplied by 2 the ratio comes still as 5.4:5.4: 2

The nearest possible rounded accuracy only possible with 8.1:8.1:3 . Whch can be taken as 8: 8: 3 comparatively.

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8)

Empirical formula of the compound given = CH

Empirical formula mass = 13 g/mol

Molar mass given = 23 g/mol

Molar formula of the compound =

(CH) 2

Molecular formula =

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9)

% mass of Na in NaCl = 39%

So 100 g of NaCl contains 39 g of sodium.

mass of sodium in 22 g of NaCl =

= 8.58 g

The woman consumes 8.58 g of sodium by consuming 22 g of NaCl