U8 part 1

Multiple Choice

What is the main difference between a molecular formula and an empirical formula?

• A molecular formula shows the simplest whole-number ratio of atoms in a compound, while an empirical formula shows the actual number of atoms in a molecule.

• A molecular formula shows the actual number of atoms in a molecule, while an empirical formula shows the simplest whole-number ratio of atoms in a compound.

• A molecular formula and an empirical formula are always the same.

• A molecular formula only applies to ionic compounds.

Open Ended

Why is it important to understand the difference between pure substances and mixtures when studying matter?

Multiple Choice

Which of the following best describes percent composition in chemistry?

• The ratio of the mass of each element to the total mass of the compound, expressed as a percentage.

• The number of atoms of each element in a compound.

• The physical state of a compound at room temperature.

• The method used to separate mixtures into pure substances.

Open Ended

A chemist is analyzing a sample and determines that it contains 1.71 g C and 0.287 g H. What is the empirical formula for the substance? What are 3 possible molecular formulas for the substance?

Open Ended

Explain the process of deriving an empirical formula from the percent composition of a compound. Why is this process important in chemistry?

Multiple Choice

Which of the following mixtures are homogeneous? Select all that apply: a. pepperoni pizza, b. perfume, c. sandwich, d. coffee, e. ketchup, f. a glass of salt water, g. boba tea, h. salad, i. gasoline.

• b, d, f, i

• a, c, e, h

• b, e, g, i

• d, f, h, i

Open Ended

Explain how covalent and ionic substances dissolve differently in water, using the diagrams and equations provided.

Multiple Choice

Which of the following substances is ionic?

• CH4

• NH4Br

• MgCl2

• KNO3

Multiple Select

Which of the following covalent molecules is polar?

• N2

• CO2

• Ammonia

• Water

Open Ended

A 355 mL soft drink contains 0.133 mol of sucrose. What is the concentration of sucrose in the beverage?

Open Ended

How many grams of NaCl are contained in a 0.250 L of a 5.30 M solution?

Open Ended

How does understanding percent composition help in identifying unknown compounds or substances in real-world scenarios?

Multiple Choice

What is the main difference between a pure substance and a mixture?

• A pure substance has a constant composition, while a mixture does not.

• A mixture has a constant composition, while a pure substance does not.

• Both pure substances and mixtures have constant compositions.

• Pure substances cannot be separated by physical changes, but mixtures can.

Open Ended

If the concentration of H2SO4 is 2 M, what volume of solution contains 5 g of H2SO4?

Labelling

Which of these molecules is joined by an ionic bond vs a covalent bond?

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Ionic Bond

Covalent Bond

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Click on the covalent bond

Multiple Choice

Will this molecule be polar or nonpolar? PH₃

• polar
• nonpolar

Labelling

2 NaCl + Pb(NO₃)₂ --> 2 NaNO₃ + PbCl₂

How many grams of lead (II) chloride can be formed from 32.5 g sodium chloride? (place the items in the proper places for solving the equation)

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1 mol PbCl2

163.85 g PbCl2

58.44 g NaCl

1 mol NaCl

278.10 g PbCl2

2 mol PbCl2

2 mol NaCl

Labelling

Set up the following problem:

N₂ + 3 H₂ --> 2 NH₃

How many moles of NH₃ are consumed when 83.42 grams of hydrogen gas is also consumed?

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2 mol NH₃

1 mole H₂

22.4 L NH₃

3 mol H₂

83.42 g H₂

2.02 g H₂

83.42 g NH₃

1 mol NH₃

1 mole N₂

17.03 g NH₃

Drag and Drop

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solution

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solute

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molarity