Graded Assignment
SCI303B: Chemistry | Unit 4 | Lesson 8: Mid-Unit Test
| Name: | Date: |
Graded Assignment
Mid-Unit Test, Part 2
Answer the questions below. Unless otherwise instructed, you may use a scientific calculator and refer to the periodic table in the Chemistry: Problems and Solutions book for this test.
(5 points)
| Score |
1. Describe what happens when two substances at different temperatures come into contact. Describe how the law of conservation of energy applies to this system.
Answer:
(8 points)
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2. You used a calorimeter in the Heat Transfer lab. Explain how the calorimeter works, and how you can calculate the heat given off or absorbed by the reaction being studied.
Answer:
(8 points)
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3. A calorimeter contains 500 g of water at 25°C. You place a hand warmer containing 100 g of liquid sodium acetate (NaAC) inside the calorimeter. When the sodium acetate finishes crystallizing, the temperature of the water inside the calorimeter is 32.2°C. The specific heat of water is
4.18 J/g-°C. What is the enthalpy of fusion (ΔHf) of the sodium acetate? Show your work.
Answer:
| Your Score | ___ of 21 |
Graded Assignment
SCI303B: Chemistry | Unit 3 | Lesson 11: Unit Test
| Name: | Date: |
Graded Assignment
Unit Test, Part 2
Answer the questions below. You may use a scientific calculator for this test. When you have finished, submit this assignment to your teacher by the due date for full credit.
(5 points)
| Score |
1. Explain what is in a buffer. Discuss the function of a buffer. How will pH change when small amounts of acids or bases are added to the buffer solution?
Answer:
(5 points)
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2. Cooks use baking soda to make cakes light and fluffy. You might have used baking soda yourself. Baking soda is NaHCO3. A 0.1 M solution of baking soda in water has a [H+] of about 4.0 × 10–9. (You may prefer to think of the hydronium ion concentration, [H3O+], as 4.0 × 10–9.) Write the formula for the calculation of pH, and then show each step as you calculate the pH of a 0.1 M solution of baking soda.
Answer:
(5 points)
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3. Before tackling this problem, be sure you know how to find the antilog of a number using a scientific calculator.
A solution has a pH of 5.4. Write the formula you will use to calculate the [H+] and then show all your work leading to the determination of [H+].
Answer:
| Your Score | ___ of 15 |
Graded Assignment
SCI303B: Chemistry | Unit 9 | Lesson 4: Semester Test
| Name: | Date: |
Graded Assignment
Semester Test, Part 2
Answer the questions below. When you have finished, submit this assignment to your teacher by the due date for full credit.
(5 points)
| Score |
1. What is Charles’s law?
· State the definition of the law in words.
· What are the assumptions of Charles’s law?
· Write mathematical equations that represent the law.
· What can you do with Charles’s law?
· Using a gas-filled balloon as an example, describe what happens to the gas molecules that behave according to Charles’s law.
Answer:
(5 points)
| Score |
2. Draw a structural formula for 3,4-hexene (C6H12), which has a double bond between the number 3 and 4 carbons in the chain. What class of compound is it, and what feature distinguishes it as that class?
Answer:
(5 points)
| Score |
3. Besides the major types of radioactive decay, there are two others: positron emission and electron capture.
· Compare and contrast positrons with electrons.
· Explain how positron emission works and how it causes transmutations.
· Explain how electron capture works and how it causes transmutations.
· Compare the transmutations caused by positron emissions and electron capture.
Answer:
| Score |
(5 points)
4. A calorimeter contains 500 g of water at 25°C. You place a hand warmer containing 200 g of liquid sodium acetate inside the calorimeter. When the sodium acetate finishes crystallizing, the temperature of the water inside the calorimeter is 39.4°C. The specific heat of water is 4.18 J/g-°C. What is the enthalpy of fusion (Hf) of the sodium acetate? (Show your work.) Where necessary, use q = mHf.
Answer:
| Your Score | ___ of 20 |
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