Q1. Give an example of each of the following:

Background

Topic: Classification of Matter, Atomic Structure, Chemical Properties

This question tests your understanding of basic chemistry concepts, including types of particles, mixtures, compounds, elements, and physical/chemical properties.

Key Terms:

• Subatomic particle: Particles found within atoms (protons, neutrons, electrons).

• Homogeneous mixture: Uniform composition throughout (e.g., salt water).

• Heterogeneous mixture: Non-uniform composition (e.g., salad).

• Ionic compound: Compound formed from ions (e.g., NaCl).

• Atomic symbol: Notation for an element, often with mass and atomic numbers.

• Cation/Anion: Positively/negatively charged ions.

• Physical change: Change that does not alter chemical identity (e.g., melting).

• Pure substance: Material with uniform and definite composition (element or compound).

• Diatomic element: Element that exists as two atoms bonded together (e.g., O2).

• Gaseous compound/element: Compound or element in the gas phase.

• Solid compound: Compound in solid state.

• Nonmetal: Element that lacks metallic properties.

• Physical property: Observable/measurable property (e.g., boiling point).

• Neutrons: Neutral subatomic particles in nucleus.

• Alkaline earth metal: Group 2 element.

• Halogen: Group 17 element.

• Covalent compound: Compound formed by sharing electrons.

• Strong electrolyte: Substance that dissociates completely in water.

• Solubility: Ability to dissolve in a solvent.

• Acid/Base: Substances with characteristic properties (e.g., vinegar, baking soda).

• Valence electrons: Electrons in outermost shell.

• Transition/representative element: Elements in d-block/p-block.

• Rutherford's model: Atom has a dense nucleus.

Step-by-Step Guidance

1. For each part, identify the definition or characteristic of the term (e.g., "subatomic particle in the nucleus" refers to protons and neutrons).

2. Recall or look up common examples that fit each description (e.g., for "homogeneous mixture," think of solutions like salt water).

3. For atomic symbol questions, use the periodic table to determine the element based on protons, and calculate the atomic symbol with mass number and charge.

4. For properties and changes, distinguish between physical and chemical properties/changes (e.g., melting is physical, burning is chemical).

5. For elements and compounds, use the periodic table to identify groups (alkaline earth metals, halogens, transition elements) and their periods.

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Q2. What is the concentration, in mass percent, of a solution prepared from 75.0g NaCl in 250.0g of water?

Background

Topic: Solution Concentration (Mass Percent)

This question tests your ability to calculate mass percent concentration for a solution.

Key formula:

Where:

• Mass of solute = mass of NaCl

• Mass of solution = mass of NaCl + mass of water

Step-by-Step Guidance

1. Identify the mass of solute:

2. Identify the mass of solvent:

3. Calculate the total mass of the solution:

4. Set up the mass percent formula:

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Q3. A 25 lb child requires 0.005g per kg of body weight of a drug. Calculate the number of grams of the drug the child requires. If the drug has a molar mass of 255 g/mol, how many moles of drug does the child require?

Background

Topic: Unit Conversion, Dosage Calculation, Moles

This question tests your ability to convert units (pounds to kilograms), calculate dosage, and convert mass to moles.

Key formulas:

Step-by-Step Guidance

1. Convert the child's weight from pounds to kilograms:

2. Calculate the total drug required:

3. Use the calculated mass to find moles:

Try solving on your own before revealing the answer!

Q4. 2 Al (s) + 3 Cl2 (g) → 2 AlCl3 (s) How many grams of aluminum chloride are formed when 650.02g of chlorine reacts? What is the classification of the reaction? Which element is being oxidized?

Background

Topic: Stoichiometry, Reaction Types, Redox Chemistry

This question tests your ability to use stoichiometry to calculate product mass, classify reactions, and identify oxidation.

Key formulas:

Use the balanced equation to relate moles of Cl2 to moles of AlCl3.

Step-by-Step Guidance

1. Calculate moles of Cl2 using its molar mass:

2. Use the stoichiometric ratio from the equation:

3. Calculate moles of AlCl3 produced.

4. Convert moles of AlCl3 to grams using its molar mass.

5. For classification, identify if the reaction is synthesis, decomposition, etc. For oxidation, determine which element increases its oxidation state.

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Q5. What is the molarity of a solution made by diluting 50.0 mL of a 5.5M solution to a volume of 160.0 mL?

Background

Topic: Solution Dilution, Molarity

This question tests your ability to use the dilution equation to find the new molarity after dilution.

Key formula:

Where:

• = initial molarity

• = initial volume

• = final molarity (unknown)

• = final volume

Step-by-Step Guidance

1. Write down the known values: , ,

2. Set up the dilution equation:

3. Solve for by rearranging:

Try solving on your own before revealing the answer!

Q6. Calculate the number of ethanol molecules in 15.20g of ethanol (CH3CH2OH).

Background

Topic: Mole Concept, Avogadro's Number

This question tests your ability to convert mass to moles and then to number of molecules.

Key formulas:

Step-by-Step Guidance

1. Calculate the molar mass of ethanol (CH3CH2OH).

2. Find the number of moles:

3. Multiply moles by Avogadro's number to get molecules:

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Q7. Calculate the molarity of a solution made by dissolving 6.785 g of sodium carbonate into a final solution of 250.0 mL.

Background

Topic: Molarity Calculation

This question tests your ability to calculate molarity from mass and volume.

Key formula:

Step-by-Step Guidance

1. Calculate the molar mass of sodium carbonate ().

2. Find moles:

3. Convert volume to liters:

4. Set up the molarity formula:

Try solving on your own before revealing the answer!

Q8. Convert 56.42 g/L to lb/gal

Background

Topic: Unit Conversion

This question tests your ability to convert between metric and imperial units.

Key conversion factors:

Step-by-Step Guidance

1. Set up the conversion:

2. Multiply through to get the value in lb/gal.

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Q9. Calculate the number of centigrams in 65.0 kg

Background

Topic: Metric Unit Conversion

This question tests your ability to convert between metric units (kg to cg).

Key conversion factors:

Step-by-Step Guidance

1. Convert kg to g:

2. Convert g to cg:

Try solving on your own before revealing the answer!

Q10. True or False. HC2H3O2 (aq) is acetic acid which is a weak acid so it is considered a weak electrolyte

Background

Topic: Acids, Electrolytes

This question tests your understanding of acid strength and electrolyte classification.

Key concepts:

• Acetic acid is a weak acid.

• Weak acids only partially ionize in water.

• Weak electrolytes conduct electricity poorly.

Step-by-Step Guidance

1. Recall the definition of a weak acid and weak electrolyte.

2. Determine if acetic acid fits these definitions.

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Q11. Convert 56.5 mL to µL

Background

Topic: Metric Unit Conversion

This question tests your ability to convert between milliliters and microliters.

Key conversion factor:

Step-by-Step Guidance

1. Multiply the number of mL by 1000 to get µL:

Try solving on your own before revealing the answer!