Chemistry Unit 1 Ch4 Revision

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CHAPTER 4 REVISION

1. How many moles of silver atoms are in 0.780 grams of silver? a) 0.78 moles
b) 0.00723 moles
c) 84.2 moles
d) 0.522 moles
2. What is the molar mass of Mg(BrO4)2?
a) 312 g mol-1
b) 232 g mol-1
c) 168.2 g mol-1
d) 477 g mol-1
3. What mass of the compound FeWO4 contains 50.0 grams of tungsten (atomic symbol W, atomic number = 74)? a) 30.0 g FeWO4
b) 304 g FeWO4
c) 82.6 g FeWO4
d) 188 g FeWO4
d) FeSO4
4. A compound contains 20.2% magnesium, 39.8% titanium, and 40.0% oxygen by mass. What is the empirical formula of this compound? a) MgTiO
b) MgTi2O3
c) Mg2TiO4
d) MgTiO3
5. Which of the following DOES NOT contain 4.00 moles of oxygen atoms? a) 2.00 moles of CO2
b) 128.0 g of SO2
c) 0.40 moles of P4O10
d) 4.00 moles of KClO3
6. A compound has an empirical formula of C2HBr. If the molar mass of the compound is 314.7 g/mol, what is the molecular formula of the compound? a) C2HBr
b) C4H2Br2
c) C6H3Br3
d) C8H4Br4

7. What is the mass percent of copper in the mineral bornite, Cu4FeS4? a) 44.4%
b) 58.0%
c) 14.5%
d) 72.4%
8. A 0.2420 sample of an unknown containing C, O, and H is burned completely. Analysis shows that 0.2265 grams of water are produced. How many grams of hydrogen were present in the 0.2420 grams of sample? a) 0.0253 grams

b) 0.2265 grams
c) 0.0127 grams
d) 0.1522 grams
9. What is the mass of 0.220 moles of AgNO3?
a) 169.9 g
b) 0.415 g
c) 0.220 g
d) 37.4 g

Short Answers

Q1.Silver consists of two isotopes:

Relative Atomic Mass| 107| 51.84|
Abundance| 109| 48.16|

Calculate the average relative atomic mass of silver.

Q2. Copper consists of two natural isotopes. The lightest isotope has a relative atomic mass of 62.9296 and the heavier isotope has a mass of 64.9278. If the average relative atomic mass of lithium is 63.546, find the abundance of each isotope.

Q3a. The following is a sketch of a mass spectrometer. Indicate what happens in each section of the mass spectrometer, labelled A to D.

B
B

D
D
C
C
A
A

Q3b. How much heavier are 100 atoms of copper compared to 100 atoms of carbon -12?

4. Table sugar is sucrose, C12H22O11. When concentrated sulfuric acid is added to sucrose, the sucrose decomposes, as the hydrogen and oxygen are removed as water, leaving behind a black column of carbon.

a. Calculate the percentage by mass of carbon in sucrose. b. Calculate the mass of carbon that would be obtained by the decomposition of 500.0g of sucrose. c. Calculate the mass of sucrose that would be required to produce a column containing 50.0g of carbon

5a. How many moles of glucose, C6H12O6 are present in 2.00 kg glucose?

5b. How many molecules in 2.00 kg glucose?

5c. How many atoms in 2.00 kg of glucose?
5d. What is the mass of 0.25 mole of glucose?

5e. What is the mass of 1.204 x 1024 molecules of glucose?

5f. A sample of glucose contains 36.0g of carbon, how many molecules of glucose are in the sample?

6. What is the mass of one water molecule?

7. Putricine H2N(CH2)4NH2 causes the smell of rotting meat.

How many molecules of putricine are present in 1.50mg of this substance?

8. When 7.532g of hydrated magnesium chloride, MgCl2.xH2O is heated strongly 3.527g of anhydrous magnesium chloride remains. Find the empirical formula of the hydrated salt.

9. Glycerol is a sweet smelling viscous liquid used to make sweets. It is also produced during the manufacture of soap and is a raw material for making dynamite. Glycerol consists of 39.1% carbon, 8.7% hydrogen and the rest is oxygen. Glycerol has a relative molecular mass of 92. Find the molecular formula of glycerol.

10. A particular hydrocarbon has an empirical formula of C4H9 and a 0.25 mol of the compound has a mass of 28.5g. What is the molecular formula of the...
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