Q1. What is a pure substance, an element, and a mixture?

Background

Topic: Classification of Matter

This question tests your understanding of how matter is categorized in chemistry, specifically the differences between pure substances, elements, and mixtures.

Key Terms:

• Pure substance: Matter with a fixed composition and distinct properties.

• Element: A pure substance that cannot be broken down into simpler substances by chemical means.

• Mixture: A combination of two or more substances where each retains its own properties.

Step-by-Step Guidance

1. Define what a pure substance is and give an example.

2. Explain what an element is and how it relates to pure substances.

3. Describe what a mixture is and how it differs from a pure substance.

4. Think of examples for each category to help clarify the differences.

Try answering in your own words before revealing the answer!

Q2. How do solids, liquids, and gases differ?

Background

Topic: States of Matter

This question tests your understanding of the physical properties and particle arrangements in the three main states of matter.

Key Terms:

• Solid: Definite shape and volume; particles are closely packed and vibrate in place.

• Liquid: Definite volume but no definite shape; particles are close but can move past each other.

• Gas: No definite shape or volume; particles are far apart and move freely.

Step-by-Step Guidance

1. Describe the arrangement and movement of particles in a solid.

2. Explain how liquids differ from solids in terms of particle movement and shape.

3. Discuss how gases differ from both solids and liquids in terms of volume, shape, and particle spacing.

Try to describe each state before checking the answer!

Q3. What are physical and chemical changes? Give one example of each.

Background

Topic: Types of Changes in Matter

This question tests your ability to distinguish between changes that alter the form of a substance versus those that change its chemical identity.

Key Terms:

• Physical change: A change in form or appearance without changing the substance's identity.

• Chemical change: A change that results in the formation of new substances with different properties.

Step-by-Step Guidance

1. Define what a physical change is and think of a common example.

2. Define what a chemical change is and consider an example where a new substance forms.

3. Compare the two types of changes to clarify the difference.

Try to come up with your own examples before revealing the answer!

Q4. Explain the difference between a homogeneous and a heterogeneous mixture.

Background

Topic: Types of Mixtures

This question tests your understanding of how mixtures can be uniform or non-uniform in composition.

Key Terms:

• Homogeneous mixture: Uniform composition throughout (also called a solution).

• Heterogeneous mixture: Non-uniform composition; different parts are visible.

Step-by-Step Guidance

1. Define what makes a mixture homogeneous and give an example.

2. Define what makes a mixture heterogeneous and provide an example.

3. Compare the two types to highlight the key difference.

Try to think of examples before revealing the answer!

Q5. What are prefix multipliers? List two examples.

Background

Topic: Metric System and Units

This question tests your knowledge of how prefixes are used to indicate multiples or fractions of units in the metric system.

Key Terms:

• Prefix multiplier: A prefix that indicates a specific power of ten for a unit (e.g., kilo-, milli-).

Step-by-Step Guidance

1. Define what a prefix multiplier is in the context of the metric system.

2. List two common examples, including their symbols and values.

Try to recall two examples before revealing the answer!

Q6. What is the mass of 2.00 L of an intravenous glucose solution with a density of 1.15 g/mL?

Background

Topic: Density Calculations

This question tests your ability to use density as a conversion factor to find mass from volume.

Key Formula:

Rearranged:

Key Terms:

• Density (g/mL)

• Volume (L or mL)

• Mass (g)

Step-by-Step Guidance

1. Convert the volume from liters to milliliters, since the density is in g/mL.

2. Set up the formula: .

3. Plug in the values for density and volume (in the correct units).

4. Multiply to find the mass, but stop before calculating the final value.

Try solving on your own before revealing the answer!

Q7. Mercury has a specific gravity of 13.6. How many milliliters of mercury have a mass of 0.35 kg?

Background

Topic: Specific Gravity and Density

This question tests your ability to use specific gravity to find the volume of a substance given its mass.

Key Terms and Formulas:

• Specific gravity: Ratio of the density of a substance to the density of water (at 4°C, 1.00 g/mL).

• Density of mercury = Specific gravity × Density of water

• Rearranged:

Step-by-Step Guidance

1. Convert the mass from kilograms to grams.

2. Calculate the density of mercury using its specific gravity.

3. Set up the formula to solve for volume: .

4. Plug in the values, but stop before the final calculation.

Try to finish the calculation before revealing the answer!

Q8. The density of a solution is 1.18 g/mL. Its specific gravity is

Background

Topic: Density and Specific Gravity

This question tests your understanding of the relationship between density and specific gravity.

Key Terms and Formula:

• Specific gravity:

• Density of water at 4°C = 1.00 g/mL

Step-by-Step Guidance

1. Write the formula for specific gravity.

2. Plug in the density of the solution and the density of water.

3. Set up the division, but do not calculate the final value yet.

Try to compute the value before revealing the answer!

Q9. A clinic had 30 patients on Friday morning. If 24 patients were given flu shots, what percentage of the patients received flu shots?

Background

Topic: Percent Calculations

This question tests your ability to calculate percentages from given data.

Key Formula:

Step-by-Step Guidance

1. Identify the total number of patients (whole) and the number who received flu shots (part).

2. Set up the percentage formula using these values.

3. Multiply by 100%, but stop before calculating the final percentage.

Try to finish the calculation before revealing the answer!

Q10. An alloy contains 57 g of pure silver and 23 g of pure copper. What is the percentage of silver in the alloy?

Background

Topic: Percent Composition

This question tests your ability to calculate the percent by mass of a component in a mixture or alloy.

Key Formula:

Step-by-Step Guidance

1. Add the masses of silver and copper to find the total mass of the alloy.

2. Set up the formula for percent silver using the mass of silver and the total mass.

3. Multiply by 100%, but do not calculate the final value yet.

Try to solve before revealing the answer!

Q11. A collection of coins contains 9 nickels, 6 quarters, and 5 dimes. What is the percentage of dimes in the collection?

Background

Topic: Percent Composition (Counting)

This question tests your ability to calculate the percent of a specific item in a group.

Key Formula:

Step-by-Step Guidance

1. Add up the total number of coins.

2. Set up the formula for percent dimes using the number of dimes and the total number of coins.

3. Multiply by 100%, but stop before the final calculation.

Try to finish the calculation before revealing the answer!

Q12. A saline solution has a mass of 24 g, of which 2.8 g is sodium chloride. What percent of the solution is sodium chloride?

Background

Topic: Percent Composition by Mass

This question tests your ability to calculate the percent by mass of a solute in a solution.

Key Formula:

Step-by-Step Guidance

1. Identify the mass of sodium chloride (solute) and the total mass of the solution.

2. Set up the formula for percent sodium chloride.

3. Multiply by 100%, but do not calculate the final value yet.

Try to solve before revealing the answer!

Q13. What is energy? What is work? List some examples of each.

Background

Topic: Energy and Work

This question tests your understanding of the definitions and examples of energy and work in chemistry.

Key Terms:

• Energy: The capacity to do work or produce heat.

• Work: The result of a force acting over a distance.

Step-by-Step Guidance

1. Define energy in your own words and think of a few examples (e.g., light, heat, chemical energy).

2. Define work and consider examples where force causes movement (e.g., lifting a book).

3. List at least two examples for each term.

Try to come up with your own examples before revealing the answer!

Q14. What is kinetic energy? What is potential energy? List some examples of each.

Background

Topic: Forms of Energy

This question tests your understanding of the two main types of energy and their examples.

Key Terms:

• Kinetic energy: Energy of motion.

• Potential energy: Stored energy due to position or composition.

Step-by-Step Guidance

1. Define kinetic energy and think of examples involving movement.

2. Define potential energy and consider examples involving stored energy.

3. List at least two examples for each type.

Try to list your own examples before revealing the answer!

Q15. What is the SI unit of energy? List some other common units of energy.

Background

Topic: Units of Energy

This question tests your knowledge of the standard and alternative units used to measure energy.

Key Terms:

• SI unit of energy: Joule (J)

• Other units: calorie (cal), kilojoule (kJ), kilocalorie (kcal)

Step-by-Step Guidance

1. Identify the SI unit for energy.

2. List at least two other units commonly used to measure energy.

3. Consider where each unit might be used (e.g., food energy, physics).

Try to recall the units before revealing the answer!

Q16. What is heat capacity?

Background

Topic: Heat and Temperature

This question tests your understanding of how substances absorb heat and the concept of heat capacity.

Key Terms:

• Heat capacity: The amount of heat required to raise the temperature of an object by 1°C.

Step-by-Step Guidance

1. Define heat capacity in your own words.

2. Consider how heat capacity differs from specific heat capacity.

3. Think of why heat capacity is important in chemistry.

Try to define it before revealing the answer!

Q17. Suppose you find a penny (minted before 1982, when pennies were almost entirely copper) in the snow. How much heat is absorbed by the penny as it warms from the temperature of the snow, which is -8.0 ºC, to the temperature of your body, 37.0 ºC? Assume the penny is pure copper and has a mass of 3.10 g.

Background

Topic: Heat Transfer and Specific Heat

This question tests your ability to calculate the amount of heat absorbed using specific heat, mass, and temperature change.

Key Formula:

• = heat absorbed (J)

• = mass (g)

• = specific heat capacity (J/g°C)

• = change in temperature (°C)

Step-by-Step Guidance

1. Identify the mass of the penny, the specific heat of copper, and the initial and final temperatures.

2. Calculate the temperature change () by subtracting the initial temperature from the final temperature.

3. Set up the formula with the known values.

4. Multiply the values together, but stop before calculating the final value for .

Try to finish the calculation before revealing the answer!

Q18. A 32.5 g cube of aluminum initially at 45.8 ºC is submerged into 105.3 g of water at 15.4 ºC. What is the final temperature of both substances at thermal equilibrium? (Assume that the aluminum and the water are thermally isolated from everything else.)

Background

Topic: Calorimetry and Heat Exchange

This question tests your ability to use the principle of conservation of energy to solve for the final temperature when two substances at different temperatures are mixed.

Key Formula:

For each substance:

• Aluminum: g, J/g°C, °C

• Water: g, J/g°C, °C

Step-by-Step Guidance

1. Write the heat lost by aluminum:

2. Write the heat gained by water:

3. Set up the equation:

4. Plug in the known values and set up the equation to solve for , but stop before solving for $T_f$.

Try to solve for before revealing the answer!

Q19. To determine whether a shiny gold-colored rock is actually gold, a chemistry student decides to measure its heat capacity. She first weighs the rock and finds it has a mass of 4.7 g. She then finds that upon absorption of 57.2 J of heat, the temperature of the rock rises from 25 ºC to 57 ºC. Find the specific heat capacity of the substance composing the rock and determine whether the value is consistent with the rock being pure gold.

Background

Topic: Specific Heat Capacity Calculation

This question tests your ability to calculate specific heat capacity from experimental data and compare it to known values.

Key Formula:

Rearranged:

• = heat absorbed (J)

• = mass (g)

• = change in temperature (°C)

Step-by-Step Guidance

1. Calculate the temperature change () by subtracting the initial temperature from the final temperature.

2. Plug the values for , , and into the formula for specific heat capacity.

3. Set up the calculation, but stop before finding the final value.

4. Compare the calculated value to the specific heat of gold (0.128 J/g°C) to determine if the rock could be gold.

Try to calculate before revealing the answer!

Q20. A 55.0 g aluminum block initially at 27.5 ºC absorbs 725 J of heat. What is the final temperature of the aluminum?

Background

Topic: Heat Transfer and Specific Heat

This question tests your ability to use the specific heat formula to solve for the final temperature after heat is absorbed.

Key Formula:

Rearranged:

Final temperature:

• = heat absorbed (J)

• = mass (g)

• = specific heat of aluminum (0.903 J/g°C)

• = initial temperature (°C)

Step-by-Step Guidance

1. Identify the values for , , , and .

2. Calculate using .

3. Add to the initial temperature to find the final temperature, but stop before the final calculation.

Try to solve for the final temperature before revealing the answer!