Download Tuesday, June 03, 2008 1. Given the incomplete equation

Formulas
Name: ____________________________________
Tuesday, June 03, 2008
1.
Given the incomplete equation: 2N 2O5(g)
_____
Which set of products completes and balances the incomplete equation?
1. 2N2(g) + 3H2(g)
2. 2N2(g) + 2O2(g)
3. 4NO2(g) + O2(g)
4. 4NO(g) + 5O2(g)
2.
Base your answer to the question on the information below.
Ozone gas, O 3, can be used to kill adult insects in storage bins for grain without damaging the grain. The
ozone is produced from oxygen gas, O2, in portable ozone generators located near the storage bins. The
concentrations of ozone used are so low that they do not cause any environmental damage. This use of
ozone is safer and more environmentally friendly than a method that used bromomethane, CH3Br.
However, bromomethane was more effective than ozone because CH3Br killed immature insects as well
as adult insects.
Adapted From: The Sunday Gazette (Schenectady, NY) 3/9/03
Figure 1
Determine the total number of moles of CH3Br in 19 grams of CH3Br (gram-formula mass = 95 grams/mol).
Answer:
mol
Formulas
3.
Base your answer to the question on the information below.
The particle diagrams below represent the reaction between two nonmetals, A2 and Q2
Figure 2
Using the symbols A and Q, the chemical formula of the product could be written as
1. AQ
3. AQ2
2. A2Q
4. A2Q2
4.
Given the equation:
If 8.0 moles of O2 are completely consumed, what is the total number of moles of H2O produced?
mol
Formulas
5.
Which particle diagram represents one pure substance, only?
1.
3.
2.
4.
6.
Given the reaction: CH4(g) + 2O2(g)
CO2(g) + 2H2O(g)
How many moles of oxygen are needed for the complete combustion of 3.0 moles of CH4(g)?
1. 6.0 moles
2. 2.0 moles
3. 3.0 moles
4. 4.0 moles
7.
What is the molecular formula of a compound that has a molecular mass of 54 and the empirical formula C 2H3?
1. C2H3
2. C4H6
3. C6H9
4. C8H12
8.
Given the balanced equation representing a reaction:
What is the mole ratio of H 2(g) to HF(g) in this reaction?
1. 1:1
3. 2:1
2. 1:2
4. 2:3
Formulas
9.
What is the gram formula mass of Li 2SO4?
1. 54g
2. 55g
3. 110g
4. 206g
10.
What is the percent by mass of nitrogen in the compound NH 4NO3 (formula mass = 80.)?
1. 5.7%
2. 18%
3. 29%
4. 35%
11.
Which substance represents a compound?
1. C(s)
2. Co(s)
3. CO(g)
4. O2(g)
12.
Two alcohols that are used in our everyday lives are rubbing alcohol and ethylene glycol. Rubbing alcohol
is used as an antiseptic. Ethylene glycol is the main ingredient in antifreeze, which is used in automobile
cooling systems.
Figure 3
What is the gram-formula mass of ethylene glycol, C 2H4(OH)2?
g/mol
13.
Which pair consists of a molecular formula and its corresponding empirical formula?
1. C2H2 and CH3CH3
3. P4O10 and P2O5
2. C6H6 and C2H2
4. SO2 and SO3
Formulas
14.
Given the balanced equation:
2 C4H10(g) + 13 O2 (g) → 8 CO2 (g) + 10 H2 O(g)
What is the total number of moles of O2 (g) that must react completely with 5.00 moles of C4H10(g )?
1. 10.0
2. 20.0
3. 26.5
4. 32.5
15.
Which process represents a chemical change?
1. melting of ice
2. corrosion of copper
3. evaporation of water
4. crystallization of sugar
16.
Given the reaction: 6 CO2 + 6 H2O → C2H12O6 + 6 O 2
What is the total number of moles of water needed to make 2.5 moles of C2H12O6?
1. 2.5
2. 6.0
3. 12
4. 15
17.
Antacids can be used to neutralize excess stomach acid. Brand A antacid contains the acid neutralizing agent
magnesium hydroxide, Mg(OH)2. It reacts with HCl(aq) in the stomach, according to the following balanced equation:
If a person produces 0.050 mole of excess HCl in the stomach, how many moles of Mg(OH) 2 are needed to neutralize
this excess hydrochloric acid?
mole(s)
Formulas
18.
Given the equation:
__Ca 2+ (aq) + __PO43- (aq)
__Ca3(PO4)2(s)
When the equation is correctly balanced, the sum of the total charge of the reactants is
1. 0
2. +2
3. -3
4. +6
19.
What is the empirical formula of the compound whose molecular formula is P 4O10?
1. PO
2. PO2
3. P2O5
4. P8O20
20.
Which pair of formulas correctly represents a molecular formula and its corresponding empirical formula?
1. C2H2 and CH
2. C3H4 and CH2
3. C4H6 and CH
4. C5H8 and C2H2
21.
Which substance has the same molecular and empirical formulas?
1. C6H4
2. C2H4
3. CH4
4. C6H12O6
22.
Given the reaction: 4NH 3 + 5O2 → 4NO + 6H2 O
What is the total number of moles of NO produced when 1.0 mole of O2 is completely consumed?
1. 1.0 mole
2. 1.2 moles
3. 0.80 mole
4. 4.0 moles
Formulas
23.
Which two substances can not be broken down by chemical change?
1. C and CuO
3. CO2 and CuO
2. C and Cu
4. CO2 and Cu
24.
Which statement describes a chemical property of oxygen?
1. Oxygen has a melting point of 55 K.
2. Oxygen can combine with a metal to produce a compound.
3. Oxygen gas is slightly soluble in water.
4. Oxygen gas can be compressed.
25.
What is the correct IUPAC name for the compound NH 4Cl?
1. nitrogen chloride
2. nitrogen chlorate
3. ammonium chloride
4. ammonium chlorate
26.
Element X reacts with iron to form two different compounds with the formulas FeX and Fe2X3. To which group on the
Periodic Table does element X belong?
1. Group 8
3. Group 13
2. Group 2
4. Group 16
27.
Which equation is correctly balanced?
1. H2 + O 2 → H2O
2. Ca + Cl2 → CaCl
3. 2H2 + O 2 → 2H2O
4. Ca + Cl2 → Ca2Cl
Formulas
28.
Which equation shows a conservation of mass?
1. Na + Cl2 → NaCl
3. H2O → H2 + O 2
2. Al + Br2→ AlBr3
4. PCl5 → PCl3 + Cl2
29.
Which quantity is represented by the symbol He?
1. 1 gram of helium
2. 1 liter of helium
3. 1 mole of helium
4. 1 atomic mass unit of helium
30.
An unknown element X can form a compound with the formula XBr3. In which group on the Periodic Table would
element X be found?
1. 1
2. 2
3. 13
4. 14
31.
What is the empirical formula of a compound with the molecular formula N 2O4?
1. NO
2. NO2
3. N2O
4. N2O3
32.
A hydrate is a compound that includes water molecules within its crystal structure. During an experiment to determine
the percent by mass of water in a hydrated crystal, a student found the mass of the hydrated crystal to be 4.10 grams.
After heating to constant mass, the mass was 3.70 grams. What is the percent by mass of water in this crystal?
1. 90.%
2. 11%
3. 9.8%
4. 0.40%
Formulas
33.
Base your answer to the question on the particle diagrams below, which show atoms and/or molecules in three
different samples of matter at STP.
When two atoms of y react with one atom of z, a compound forms. Using the number of atoms shown in sample 2,
what is the maximum number of molecules of this compound that can be formed?
At most
molecule(s)
34.
Given the balanced equation:
What is the total number of moles of CO2 formed when 20. moles of HCl is completely consumed?
1. 5.0 mol
3. 20. mol
2. 10. mol
4. 40. mol
Formulas
35.
Given the balanced equation:
4Al(s) + 3O 2(g) → 2Al2O3(s)
What is the total number of moles of O2(g) that must react completely with 8.0 moles of Al(s) in order to form Al2O3
(s)?
mol
36.
In the 19th century, Dmitri Mendeleev predicted the existence of a then unknown element X with a mass of 68. He
also predicted that an oxide of X would have the formula X2O3. On the modern Periodic Table, what is the group
number and period number of element X?
Group number:
Period:
37.
Which set of procedures and observations indicates a chemical change?
1. Ethanol is added to an empty beaker and the ethanol
eventually disappears.
2. A solid is gently heated in a crucible and the solid
slowly turns to liquid.
3. Large crystals are crushed with a mortar and pestle
and become powder.
4. A cool, shiny metal is added to water in a beaker and
rapid bubbling occurs.
38.
Given the balanced equation representing a reaction:
4NH3 + 5O 2
4NO + 6H2O
What is the minimum number of moles of O2 that are needed to completely react with 16 moles of NH3?
1. 16 mol
3. 64 mol
2. 20. mol
4. 80. mol
Formulas
39.
What is the total mass of oxygen in 1.00 mole of Al2(CrO4)3?
1. 192 g
2. 112 g
3. 64.0 g
4. 48.0 g
40.
Base your answer to the question on the information below.
Air bags are an important safety feature in modern automobiles. An air bag is inflated in milliseconds by
the explosive decomposition of NaN3(s). The decomposition reaction produces N 2(g), as well as Na(s),
according to the unbalanced equation below.
NaN3(s)
Na(s) + N2(g)
Figure 4
Balance the equation for the decomposition of NaN 3, using the smallest whole-number coefficients.
NaN3(s)
Na(s) +
N2(g)
41.
Given the equation: 2C 2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(g)
How many moles of oxygen are required to react completely with 1.0 mole of C2H2?
1. 2.5
2. 2.0
3. 5.0
4. 10
42.
A compound has a gram formula mass of 56 grams per mole. What is the molecular formula for this compound?
1. CH2
2. C2H4
3. C3H6
4. C4H8
Formulas
43.
Which list consists of types of chemical formulas?
1. atoms, ions, molecules
2. metals, nonmetals, metalloids
3. empirical, molecular, structural
4. synthesis, decomposition, neutralization
44.
What is the gram formula mass of Ca 3(PO4)2?
1. 135 g/mol
2. 215 g/mol
3. 278 g/mol
4. 310. g/mol
45.
Base your answer to the question on the information below.
In preparing to titrate an acid with a base, a student puts on goggles and an apron. The student uses burets
to dispense and measure the acid and the base in the titration. In each of two trials, a 0.500 M NaOH(aq)
solution is added to a flask containing a volume of HCl(aq) solution of unknown concentration.
Phenolphthalein is the indicator used in the titration. The calculated volumes used for the two trials are
recorded in the table below.
Figure 5
Based on the information given in the table, how many significant figures should be shown in the calculated molarity
of the HCl(aq) solution used in trial 2?
Answer:
significant figures
Formulas
46.
Which pair is classified as chemical substances?
1. mixtures and solutions
2. compounds and solutions
3. elements and mixtures
4. compounds and elements
47.
What is the total number of moles of oxygen atoms present in one mole of Mg(ClO3)2?
1. 5
2. 2
3. 3
4. 6
48.
The gram formula mass of NH 4Cl is
1. 22.4 g/mole
2. 28.0 g/mole
3. 53.5 g/mole
4. 95.5 g/mole
49.
Given the balanced equation representing the reaction between propane and oxygen:
C3H- + 5O 2
3CO2 + 4H2O
According to this equation, which ratio of oxygen to propane is correct?
1.
2.
3.
4.
Formulas
50.
Which type of matter is composed of two or more different elements that are chemically combined in a definite ratio?
1. a solution
2. a compound
3. a homogeneous mixture
4. a heterogeneous mixture
Formulas
Answer Key for Formulas
1. 3
2. 0.20
3. 3
4. 16
5. 1
6. 1
7. 2
8. 2
9. 3
10. 4
11. 3
12. 62
13. 3
14. 4
15. 2
16. 4
17. 0.025
18. 1
19. 3
20. 1
21. 3
22. 3
23. 2
24. 2
25. 3
26. 4
27. 3
28. 4
29. 3
30. 3
31. 2
32. 3
33. 2
34. 2
35. 6
36. 13, 4
37. 4
38. 2
39. 1
40. 2, 2, 3
41. 1
42. 4
43. 3
44. 4
45. 3
46. 4
Formulas
47. 4
48. 3
49. 2
50. 2