Chem Q4 Benchmark Study Guide
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Hello students,
This quiz is a study guide and provides practice problems and correct answer explanations in preparation for the Q4 Chemistry Benchmark.
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Question 1 of 20
1. Question
Alkanes are hydrocarbons that contain:
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Remember — KANES, KENES and KYNES
alk-A-nes, alk-E-nes and alk-Y-nes are in alphabetical order and have
alkanes – all single C-C bonds
alkenes – one or more double C-C bonds, the rest are single bonds
alkynes – one or more triple C-C bonds, the rest may be any combination of single or double bonds. -
Question 2 of 20
2. Question
Which compounds have carbon-carbon double bonds?
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Remember — KANES, KENES and KYNES
alk-A-nes, alk-E-nes and alk-Y-nes are in alphabetical order and have
alkanes – all single C-C bonds
alkenes – one or more double C-C bonds, the rest are single bonds
alkynes – one or more triple C-C bonds, the rest may be any combination of single or double bonds. -
Question 3 of 20
3. Question
A carbon atom can bond to four other atoms because it has
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Remember – Carbon has atomic number = 6 (Atomic mass is 12).
The electron configuration is 1S2 2S2 2P2. This means the 2S and 2P orbitals comprise the outer or valence shell. There are 4 electrons total in this shell 2S2 2P2. By the rule of 8, the “2” shell can hold 8 electrons so this shell can contain an additional 4 electrons provided by other atoms in covalent bonds. -
Question 4 of 20
4. Question
The simplest organic compound is
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aspirin: C9H8O4 much larger than methane
table sugar: C12H22O11 much larger than methane
salt: NaCl not an organic compound
methane: CH4 – this is the simplest hydrocarbon or organic compound -
Question 5 of 20
5. Question
Which of the following is a basic solution?
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Household ammonia is an aqueous solution of ammonia in water.
NH3(aq) + H2O = NH4+(aq) + OH-(aq)
Ammonia is a weak rather than strong electrolyte because this reaction runs both ways; ammonia reacts with water to produce ammonium and hydroxide ions, while hydroxide ions react with ammonium ions to produce ammonia and water. The reaction clearly shows that ammonia is a base* because it accepts a hydrogen ion from the water.HCl dissolved in water: Hydrochloric acid is a strong acid which dissociates completely in water.
vinegar: is a weak acid
pure water: self dissociates to form H2O + H+ + OH-, or H2O + H3O+ + OH- in concentrations of [H+] = [OH-] = 10^-7 -
Question 6 of 20
6. Question
6. When dissolved in water, all acids will
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form hydroxide ions. – nope – that’s a base
have a negative charge. incorrect – acids break into + and – ions
conduct electricity.correct – acids contribute ions when dissolved in water and the ions can move when an external voltage is applied – so an acid in solution will conduct electricity.turn blue. –WAIT!– but don’t hold your breath or you WILL turn blue!
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Question 7 of 20
7. Question
Which is the strongest electrolyte?
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a strong acid – dissociates completely when dissolved in water so it contributes the maximum number of ions. The ions are what conducts the electricity
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Question 8 of 20
8. Question
Which is an example of a neutralization reaction?
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In a neutralization reaction, charged ions combine to form uncharged neutral compounds.
H+ + OH- —–> 2H2O
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Question 9 of 20
9. Question
When a weak acid dissolves in water, the number of acid molecules that combine with water to form ions and the ions that recombine to form acid molecules
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are in equilibrium. – the definition of a weak acid or for that matter a weak base is that the reaction goes forward and reverse and eventually reaches a point where the rate of the forward reaction equals the rate of the reverse reaction.
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Question 10 of 20
10. Question
A solution that is mildly acidic would have a pH of approximately
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pH = 2: very acidic
pH = 4: still quite acidic
pH = 6: acidic but close to a neutral pH of 7 – so this is the correct answer
pH = 8: slightly basic -
Question 11 of 20
11. Question
The pH of a substance is a measure of its
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pH is defined as minus the log of the H+ concentration. In reality, when water self dissociates, it produces H3O+ hydronium ions. In the early days of chemistry these where thought to be H+ ions. They could just as easily have called it pH3O !
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Question 12 of 20
12. Question
The label on a bottle indicates that the substance inside has a pH of 13. This tells you that the substance is
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neutral pH 7
strongly acidic pH 1-4
mildly acidic pH 5-6
mildly basic pH 8-11
strongly basic pH 12-14 -
Question 13 of 20
13. Question
An example of a nonpolar molecule is
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Oils, olefins, and waxes are usually non-polar. That is why they don’t dissolve in polar solvents such as water. Non-polar means they do not have any significant charge separation Whereas water molecules have a slight charge separation due to the fact that the Oxygen pulls the electrons slightly away from the Hydrogen atoms resulting in a slight + charge on each of the Hydrogens and a slightly larger — charge on the Oxygen.
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Question 14 of 20
14. Question
A hydrogen bond is a partial covalent bond formed between two
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Recall that a water molecule has a slight charge separation caused by the Oxygen atom pulling the electrons slightly away from the Hydrogen atoms. Then the slight positive charge of the Hydrogens on another water molecule will be attracted to and stick to the negative charge on the Oxygen atom of the first water molecule. This ‘stickiness’ is caused by an electrostatic attraction and is not an orbital sharing covalent bond nor a charge transfer ionic bind. The hydrogen bond is an electrostatic stickiness.
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Question 15 of 20
15. Question
You can make a solute dissolve more quickly in a solvent by
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heating the solute: heating causes the molecules to move around more quickly resulting in more opportunities for the solute molecules to contact and interact with the solvent molecules.
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Question 16 of 20
16. Question
Which is the most concentrated solution of sodium sulfate, Na2SO4 ?
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Molarity is defined as the number of moles of solute in 1 litre of water. So the higher the Molarity, the more solute dissolved and the larger the solute concentration.
Do not confuse Molarity ‘M’ with molality ‘m’ which is the number of moles of solute dissolved in 1 kg of solvent.
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Question 17 of 20
17. Question
In an exothermic reaction, energy is transferred from
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exo means out – think exit
exothermic reactions heat goes out of the reactants to the surroundings. Combustion reactions – burning – are examples of exothermic reactions. -
Question 18 of 20
18. Question
Which statement about endothermic reactions is correct?
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endo-
combining form
internal; within.endothermic reactions absorb heat from their surroundings -example icy-hot pads (well the icy part anyway)
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Question 19 of 20
19. Question
Temperature is a measure of the average _____ energy of the particles in the object.
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Question 20 of 20
20. Question
When a chemical reaction and its reverse are occurring at the same time and at the same rate, the reaction has achieved
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