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1 chemistry. A , sand,

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1 chemistry. A , sand,
Base your answers to questions 1 through 4 on the information below and on your knowledge of
chemistry.
A student prepares two 141-gram mixtures, A and B. Each mixture consists of
, sand,
and
at 15°C. Both mixtures are thoroughly stirred and allowed to stand. The mass of each
component used to make the mixtures is listed in the data table below.
1. Describe one property of sand that would enable the student to separate the sand from the other
components in mixture B.
2. Determine the temperature at which all of the
solution.
in mixture A dissolves to form a saturated
3. Which type of mixture is mixture B?
4. State evidence from the table indicating that the proportion of the components in a mixture can vary.
Base your answers to questions 5 through 7 on the information below and on your knowledge of
chemistry.
A laboratory technician is given the table below and a sample of one of the three substances
listed in the table. The technician makes an aqueous solution with a portion of the sample. When a
conductivity tester is lowered into the solution, the lightbulb on the tester glows brightly. Another
portion of the sample is placed in a heat-resistant container that is placed in an oven at 450°C. The
sample melts.
5. Explain, in terms of ions, why an aqueous solution of potassium chromate conducts an electric current.
6. State evidence that makes it necessary to use more than one property to identify the substance given to
the technician.
7. Identify the substance given to the technician.
Base your answers to questions 8 through 11 on the information below and on your knowledge of
chemistry.
Hydrazine,
, is a compound that is very soluble in water and has a boiling point of 113°C
at standard pressure. Unlike water, hydrazine is very reactive and is sometimes used as a fuel for
small rockets. One hydrazine reaction producing gaseous products is represented by the balanced
equation below.
8. Explain, in terms of intermolecular forces, why the boiling point of hydrazine at standard pressure is
higher than the boiling point of water as standard pressure.
9. Explain, in terms of molecular polarity, why
is very soluble in water.
10. Based on Table S, determine the electronegativity difference for the N-H bond in hydrazine.
11. Compare the entropy of the products to the entropy of the reactant for this reaction.
12. Based on Table H, state the vapor pressure of ethanol at 75°C.
Base your answers to questions 13 through 15 on
the information below and on your knowledge of chemistry.
Seawater contains dissolved salts in the form of ions. Some of the ions found in seawater are
An investigation was conducted to determine the concentration of dissolved salts in
seawater at one location. A 300.-gram sample of the seawater was placed in an open container.
After a week, all the water had evaporated and 10. grams of solid salts remained in the
container.
13. Explain why the evaporation that occurred during the investigation is an endothermic process.
14. At standard pressure, compare the freezing point of seawater to the freezing point of distilled water.
15. Determine the concentration, expressed as percent by mass, of the dissolved salts in the original
sample of seawater.
Base your answers to questions 16 through 18 on on
the information below.
A 100.0-gram sample of NaCl(s) has an initial
temperature of 0°C. A chemist measures the
temperature of the sample as it is heated. Heat is
not added at a constant rate. The heating curve for
the sample is shown below.
16. Identify one line segment on the curve where the
NaCl sample is in a single phase and capable of
conducting electricity.
17. Identify one line segment on the curve where the
average kinetic energy of the particles of the NaCl
sample is changing.
18. Determine the temperature range over which the
entire NaCl sample is a liquid.
Base your answers to questions 19 and 20 on
the information and table below.
A student conducts an experiment to
determine how the temperature of water affects
the rate at which an antacid tablet dissolves in the
water. The student has three antacid tablets of the
same size and composition. The student drops
one tablet into each of three beakers containing
200. milliliters of water at different temperatures
and measures the time it takes for each tablet to
completely dissolve. The results are shown in the
table below.
19. Explain, in terms of collision theory, how water
temperature influences the rate of dissolving.
20. Describe the effect of water temperature on the rate of dissolving.
21. Base your answer to the following question on the
graph below, which represents the cooling of a
substance starting at a temperature above its boiling
point.
What is the melting point of this substance?
22. What is the total amount of heat energy, in joules,
absorbed by 25.0 grams of water when the
temperature of the water increases from 24.0°C to
36.0°C?
Base your answers to questions 23 through 25 on the information below.
Element X is a solid metal that reacts with chlorine to form a water-soluble binary compound.
23. The binary compound consists of element X and chlorine in a 1:2 molar ratio. What is the oxidation
number of element X in this compound?
24. Explain, in terms of particles, why an aqueous solution of the binary compound conducts an electric
current.
25. State one physical property of element X that makes it a good material for making pots and pans.
26. A sample of oxygen gas in one container has a volume of 20.0 milliliters at 297 K and 101.3 kPa. The
entire sample is transferred to another container where the temperature is 283 K and the pressure is
94.6 kPa. Show a correct numerical setup for calculating the new volume of this sample of oxygen
gas.
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