Introductory Chemistry Exam 1 Review – Step-by-Step Study Guidance

Q1. Which substance is a pure compound?

Background

Topic: Classification of Matter

This question tests your understanding of the difference between elements, compounds, and mixtures.

Key Terms:

• Element: A pure substance made of only one kind of atom.

• Compound: A pure substance composed of two or more elements chemically combined in a fixed ratio.

• Mixture: A combination of two or more substances that are not chemically combined.

Step-by-Step Guidance

1. Review the definitions of element, compound, and mixture.

2. Analyze each option: Is it a single element, a compound, or a mixture?

3. Remember that a pure compound must have a fixed composition and be made of more than one element.

4. Eliminate options that are elements or mixtures.

Try solving on your own before revealing the answer!

Q2. Which property of TNT is most likely a chemical property?

Background

Topic: Physical vs. Chemical Properties

This question tests your ability to distinguish between physical and chemical properties of substances.

Key Terms:

• Physical Property: A characteristic that can be observed or measured without changing the substance's identity (e.g., color, melting point).

• Chemical Property: A characteristic that describes a substance's ability to undergo a specific chemical change (e.g., flammability, reactivity).

Step-by-Step Guidance

1. Review the definitions of physical and chemical properties.

2. For each option, ask: Does observing this property require a chemical change?

3. Identify which property involves the substance changing into something new.

Try solving on your own before revealing the answer!

Q3. Which of the following is considered to be a chemical change?

Background

Topic: Physical vs. Chemical Changes

This question tests your ability to identify chemical changes, where the composition of matter changes.

Key Terms:

• Chemical Change: A process in which one or more substances are converted into new substances with different properties.

• Physical Change: A change that affects the form of a chemical substance, but not its chemical composition.

Step-by-Step Guidance

1. Review the difference between physical and chemical changes.

2. For each option, ask: Is a new substance formed?

3. Identify which process involves a chemical reaction (e.g., burning, rusting).

Try solving on your own before revealing the answer!

Q4. A 35-gram sample of potassium completely reacts with chlorine to form 67 grams of potassium chloride. How many grams of chlorine must have reacted?

Background

Topic: Law of Conservation of Mass

This question tests your understanding of mass conservation in chemical reactions.

Key Formula:

$\text{mass of reactants} = \text{mass of products}$

Step-by-Step Guidance

1. Write the equation: $\text{K (s) + Cl}_2\text{(g)} \rightarrow \text{KCl (s)}$

2. Identify the masses: Potassium = 35 g, Potassium chloride = 67 g, Chlorine = ?

3. Apply the law of conservation of mass: $\text{mass of K} + \text{mass of Cl}_2 = \text{mass of KCl}$

4. Set up the equation to solve for the unknown mass of chlorine.

Try solving on your own before revealing the answer!

Q5. Convert the boiling point of water (100.00 °C) to Kelvin.

Background

Topic: Temperature Conversions

This question tests your ability to convert Celsius temperatures to Kelvin.

Key Formula:

$K = ^\circ C + 273.15$

Step-by-Step Guidance

1. Recall the formula for converting Celsius to Kelvin.

2. Identify the Celsius temperature: $100.00^\circ C$

3. Add $273.15$ to the Celsius temperature to set up the calculation.

Try solving on your own before revealing the answer!

Q6. A European doctor reports that you have a fever of 39.2 °C. What is your fever in degrees Fahrenheit?

Background

Topic: Temperature Conversions

This question tests your ability to convert Celsius temperatures to Fahrenheit.

Key Formula:

$^\circ F = (^\circ C \times \frac{9}{5}) + 32$

Step-by-Step Guidance

1. Recall the formula for converting Celsius to Fahrenheit.

2. Identify the Celsius temperature: $39.2^\circ C$

3. Multiply the Celsius temperature by $\frac{9}{5}$.

4. Add $32$ to the result to set up the Fahrenheit temperature.

Try solving on your own before revealing the answer!

Q7. Which statement is NOT part of Dalton’s Atomic Theory?

Background

Topic: Atomic Theory

This question tests your knowledge of the main postulates of Dalton's Atomic Theory.

Key Terms:

• Dalton’s Atomic Theory: Early model describing the nature of atoms and elements.

Step-by-Step Guidance

1. Recall the four main postulates of Dalton’s Atomic Theory.

2. Compare each statement to the original theory to see which one does not fit.

3. Look for statements that reference subatomic particles or properties not known in Dalton’s time.

Try solving on your own before revealing the answer!

Q8. Which element is a halogen?

Background

Topic: Periodic Table Groups

This question tests your ability to identify halogens on the periodic table.

Key Terms:

• Halogens: Group 7A (17) elements, known for being reactive nonmetals.

Step-by-Step Guidance

1. Recall which group on the periodic table contains the halogens.

2. Identify the group numbers or symbols for Ne, O, Ca, and I.

3. Determine which element is in Group 7A (17).

Try solving on your own before revealing the answer!

Q9. Which element is a row 4 noble gas?

Background

Topic: Periodic Table Organization

This question tests your ability to identify noble gases and their positions on the periodic table.

Key Terms:

• Noble Gases: Group 8A (18), inert gases found at the far right of the periodic table.

• Row (Period): Horizontal rows on the periodic table.

Step-by-Step Guidance

1. Recall which elements are noble gases and their group number.

2. Identify which period (row) each element is in.

3. Match the noble gas in row 4.

Try solving on your own before revealing the answer!

Q10. Which statement best summarizes the nuclear model of the atom that emerged from Rutherford’s Gold foil experiment?

Background

Topic: Atomic Structure

This question tests your understanding of the nuclear model of the atom and the results of Rutherford’s experiment.

Key Terms:

• Nuclear Model: Model of the atom with a dense, positively charged nucleus and electrons around it.

• Gold Foil Experiment: Experiment that led to the discovery of the atomic nucleus.

Step-by-Step Guidance

1. Recall the main findings of Rutherford’s Gold foil experiment.

2. Identify which statement describes a dense core (nucleus) and electrons occupying most of the volume.

3. Eliminate statements that do not match the nuclear model.

Try solving on your own before revealing the answer!