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Grade 11 Chemistry > Unit 3 Test Notes > Flashcards

Unit 3 Test Notes Flashcards

1
Q

What is a limiting reagent?

A

The reactant that is completely consumed in a chemical reaction and determines how much product will be formed.

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2
Q

What is an excess reagent?

A

A reactant that is still present after the reaction goes to completion, in larger quantity than required.

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3
Q

In the reaction 2 Gc + 4 Cc + M → Sm, which reactant is the limiting reagent?

A

Marshmallows are the limiting reagent because there are not enough of them to use up all the other reactants.

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4
Q

How can companies reduce costs related to reactants?

A

By choosing the most expensive reactant to be the limiting reagent, ensuring none is wasted.

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5
Q

True or False: Complete combustion releases less energy per mole of fuel than incomplete combustion.

A

False

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6
Q

What is the first step in calculating the limiting reagent when given two quantities of reactants?

A

Use mole ratios to determine the Limiting and Excess Reagents.

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7
Q

Fill in the blank: If you have 6.0 mol of O2, you need _______ mol of CH4 to use it up.

A

3.0

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8
Q

What is the limiting reagent if you have 2.8 mol of titanium (IV) chloride and 5.4 mol of magnesium?

A

To be determined through calculations.

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9
Q

What mass of methanol can be produced from 9.80 g of carbon monoxide and 1.30 g of hydrogen?

A

To be determined through stoichiometric calculations.

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10
Q

What is the general overview of steps for a limiting reagent problem?

A
  1. Convert masses to moles
  2. Find Limiting Reagent
  3. Use Limiting Reagent to find required substance
  4. Convert to mass of required substance.
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11
Q

In the combustion of magnesium, if 6.73 g of magnesium and 8.15 g of oxygen are available, what must be identified?

A

The limiting reagent and the mass of magnesium oxide produced.

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12
Q

Fill in the blank: Complete combustion requires an _______ of oxygen.

A

excess

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13
Q

What is stoichiometry?

A

The relationship between mass and amount of reactants and products in a chemical reaction.

Stoichiometry is essential for calculating the masses of substances involved in chemical reactions.

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14
Q

What do the coefficients in a chemical equation represent?

A

The mole ratio of one chemical to another in the reaction.

This ratio is crucial for determining how much of each reactant is needed or produced.

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15
Q

What is the general outline for calculating masses in a chemical reaction?

A

Mass Compound A → Mole Compound A → Mole Compound B → Mass Compound B

This process involves converting mass to moles and using mole ratios.

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16
Q

In the reaction CO2 + 2 LiOH → Li2CO3 + 2 H2O, what is the first step to determine the mass of lithium hydroxide required?

A

Convert mass of compound given into moles.

This step is necessary to relate the mass of CO2 to the moles of LiOH.

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17
Q

What is the mass of nitrogen produced by the decomposition of sodium azide in the airbag example?

A

87.5 g.

This mass is used to determine how much sodium azide is needed to produce that amount of nitrogen.

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18
Q

What is a stoichiometric amount?

A

The predicted amount of a reactant, relative to another reactant, that will react according to the balanced chemical equation.

In stoichiometric reactions, all reactants are used up without any remaining.

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19
Q

True or False: When stoichiometric amounts of reactants are available for a chemical reaction, some reactants will remain when the reaction is complete.

A

False.

If stoichiometric amounts are used, all reactants should be consumed by the end of the reaction.

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20
Q

What happens when non-stoichiometric amounts of reactants are combined?

A

One reactant remains when the reaction is complete.

This is a common situation in chemical reactions where reactants are not perfectly balanced.

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21
Q

Fill in the blank: The study of the mass and amount relationships between reactants and products in a chemical reaction is called _______.

A

[stoichiometry]

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22
Q

What is the balanced chemical equation for the reaction that inflates an automobile airbag?

A

2 NaN3(s) → 2 Na(s) + 3 N2(g)

This reaction shows the decomposition of sodium azide to produce nitrogen gas.

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23
Q

What is the final step to determine the mass of lithium hydroxide from moles?

A

Convert moles of required compound given into mass.

This step completes the calculation by translating moles back into mass.

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24
Q

What is the definition of yield in a chemical reaction?

A

The amount of product obtained in a chemical reaction.

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25
Q

Define theoretical yield.

A

The amount of product we predict will be obtained in a chemical reaction based on stoichiometric calculations.

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26
Q

Define actual yield.

A

The amount of product that is actually obtained at the end of a laboratory procedure.

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27
Q

True or False: The actual yield in a chemical reaction is often greater than the theoretical yield.

A

False.

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28
Q

List some reasons why the actual yield may be less than the theoretical yield.

A
  • Transfer of solutions
  • Filtering precipitates
  • Splattering during heating
  • Forming undesired byproducts
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29
Q

What does percentage yield compare?

A

The actual yield in a chemical reaction to the theoretical yield.

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30
Q

Why do chemists report the percentage yield?

A

To determine how efficient or successful the reaction is at converting reactants into products.

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31
Q

Calculate the percentage yield if the theoretical yield is 10.0 kg and the actual yield is 9.0 kg.

A

90%

Percentage Yield = (Actual Yield / Theoretical Yield) x 100

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32
Q

In the reaction CO2 (g) + 3 H2 (g) → CH3OH(l) + H2O(g), what is the actual yield of methanol if 20.0 g of hydrogen produced 102.0 g of product?

A

Calculate percentage yield using the actual yield of 102.0 g and the theoretical yield based on stoichiometric calculations.

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33
Q

Fill in the blank: Limiting reagent: _______ , Excess reagent: _______.

A

[key learning term].

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34
Q

What is the empirical formula?

A

A formula that shows the simplest whole-number ratio of elements in a compound.

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35
Q

What is the molecular formula?

A

A formula that shows the element symbols and exact number of each type of atom in a molecular compound.

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36
Q

In what cases can the empirical and molecular formula be the same?

A

When the empirical formula represents the actual number of atoms in the compound.

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37
Q

If CH3 is the empirical formula, what is a possible molecular formula of this compound?

A

C2H6 or C3H9, etc.

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38
Q

What does percentage composition indicate?

A

The proportion of masses of the elements in a compound.

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39
Q

What are the steps to determine the empirical formula?

A
  1. Determine the mass of each element in the sample.
  2. Calculate the amount of each element in moles.
  3. Determine the simplest ratio of the elements in the compound.
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40
Q

How do you handle fractions when determining empirical formulas?

A

Multiply to get a whole number ratio or round to the nearest whole number if within 0.05.

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41
Q

What does the molar mass tell us in relation to the molecular formula?

A

It tells us how many atoms are in a molecule.

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42
Q

What is the empirical formula of a compound with a % composition of 21.6% sodium, 33.3% chlorine, and 45.1% oxygen?

A

To be determined through calculations.

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43
Q

What is the ratio of hydrogen to oxygen in hydrogen peroxide?

A

1:1.

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44
Q

What is the molar mass of hydrogen peroxide?

A

34.02 g/mol.

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45
Q

What is the empirical formula of a compound with a molar mass of 30.00 g/mol and an empirical formula of CH3?

A

To be determined through calculations.

46
Q

What does X represent in determining the molecular formula?

A

The number you should multiply each of the subscripts by to determine the molecular formula.

47
Q

What technique is used to determine the molar mass of new substances?

A

Mass spectrometry.

48
Q

What happens to molecules in a mass spectrometer?

A

They break up into charged fragments when bombarded with electrons.

49
Q

What is the molecular formula of butane with % C = 82.5% and % H = 17.5%?

A

To be determined through calculations.

50
Q

Fill in the blank: The empirical formula gives the proportion of _______ of each element.

A

atoms

51
Q

True or False: The empirical formula can provide the exact number of atoms in a compound.

A

False.

52
Q

What is percentage composition?

A

The percentage, by mass, of each element in a compound

This concept is fundamental in chemistry for analyzing the composition of compounds.

53
Q

How can you calculate the percentage composition of a compound by mass?

A

By using the formula: (mass of element / total mass of compound) x 100

Ensure both masses have identical units.

54
Q

What is the total percentage of all elements in a compound?

A

100%

The percentages of each element in a compound must sum to 100%.

55
Q

How do you calculate the percentage of orange skittles in a bag of 80g containing 25g of orange skittles?

A

Percentage = (25g / 80g) x 100

This method can be applied to find the percentage of any component.

56
Q

Given a 500.00 mg tablet of Aspirin (C9H8O4) containing 300.00 mg carbon and 8.08 mg hydrogen, how do you find the percentage of oxygen?

A

First, calculate the mass of oxygen: 500.00 mg - (300.00 mg + 8.08 mg) = 191.92 mg. Then use the formula for percentage composition

The calculation illustrates how to determine the mass of an unmeasured component.

57
Q

What is sodium carbonate commonly known as?

A

Soda ash

Sodium carbonate is used in various applications, including glass manufacturing and as a cleaning agent.

58
Q

What experiment can be conducted to determine the percentage composition of sugar in bubble gum?

A

Chew the gum to dissolve the sugar, leaving behind the gum, and then calculate the percentage of sugar

This experiment illustrates practical application of percentage composition in everyday items.

59
Q

True or False: The units of mass cancel out when calculating percentage composition.

A

True

This allows the final answer to be unitless.

60
Q

Fill in the blank: The remaining mass of a compound after accounting for the known masses of its elements is called the _______.

A

mass of the unknown element

This concept is important for determining the composition of compounds with multiple elements.

61
Q

What pages should be read for extra practice on percentage composition?

A

Pages 284-287

Additional practice questions are found on page 288.

62
Q

What is the formula to convert mass to amount in moles?

A

Amount in moles (n) = mass (g) / Molar mass (g/mol)

This formula allows for the conversion of mass to moles using the molar mass of the substance.

63
Q

How do you convert a mass of 1.5 kg of calcium carbonate to an amount in moles?

A

Use the formula: n = mass (g) / Molar mass (g/mol)

Convert 1.5 kg to grams (1.5 kg = 1500 g) and then apply the molar mass of calcium carbonate.

64
Q

What is the rearranged equation to solve for mass when given amount in moles?

A

mass = amount in moles x molar mass

This rearrangement is essential for converting moles back to mass.

65
Q

How do you convert 0.36 mol of sodium sulfate into mass in grams?

A

Use the formula: m = n x M

M is the molar mass of sodium sulfate.

66
Q

What is the formula to calculate the number of entities from moles?

A

N = n x NA

N is the number of entities, n is the amount in moles, and NA is Avogadro’s number (6.02 x 10^23 entities/mol).

67
Q

If you have 10 molecules of water, how many hydrogen and oxygen atoms are there?

A

There will be 20 hydrogen atoms and 10 oxygen atoms

Each molecule of H2O contains 2 hydrogen atoms and 1 oxygen atom.

68
Q

How do you determine the number of chloride ions in 0.563 mol of calcium chloride, CaCl2?

A

Calculate using the formula: N = n x NA, with n = 0.563 mol and considering 2 chloride ions per formula unit

Each formula unit of CaCl2 has 2 chloride ions.

69
Q

What is the first step to find the number of carbon, hydrogen, and oxygen atoms in a 26.5 g sample of benzaldehyde?

A

Calculate the molar mass of benzaldehyde

This is necessary to determine the number of moles from the mass.

70
Q

What symbols represent the following quantities: amount in moles, mass, and molar mass?

A

n for amount in moles, m for mass, M for molar mass

These symbols are standard in chemical calculations.

71
Q

What is Avogadro’s Constant?

A

6.02 x 10^23 entities/mol

This constant is used to convert between moles and number of entities.

72
Q

Fill in the blank: The molar mass of NaOH is _______ g/mol.

A

[molar mass of NaOH]

The specific molar mass must be calculated based on the atomic weights of sodium, oxygen, and hydrogen.

73
Q

What is Avogadro’s Constant?

A

6.02 x 10^23 entities/mol

74
Q

Define a mole.

A

The amount of substance containing 6.02 x 10^23 entities.

75
Q

How many atoms are in one mole?

A

6.02 x 10^23 atoms

76
Q

What is the relationship between moles and grams for carbon-12?

A

1 mole = the number of atoms in 12 g of carbon-12 isotope

77
Q

What is molar mass?

A

The mass, in grams per one mole of a substance, measured in g/mol.

78
Q

How do you calculate the molar mass of a compound?

A

Add together the molar mass of each individual atom in the compound.

79
Q

Fill in the blank: The molar mass of water (H2O) is _______.

A

18.015 g/mol

80
Q

What is the molar mass of nitrogen gas (N2)?

A

14.007 g/mol x 2 = 28.014 g/mol

81
Q

How is the number of formula units in a sample calculated?

A

Use the unit conversion factor N_A = 6.02 x 10^23 entities/mol.

82
Q

True or False: 1 mole of sodium chloride contains 6.02 x 10^23 formula units of NaCl.

A

True

83
Q

What analogy is used to represent the size of a mole?

A

The Green Pea Analogy

84
Q

What is the molar mass of (NH4)3PO4?

A

The sum of the molar masses of its constituent atoms.

85
Q

How many entities are in 5 moles of NaCl?

A

5 x 6.02 x 10^23 entities

86
Q

List the steps to calculate molar mass.

A
  • Write the chemical formula
  • Determine the number of atoms or ions of each element
  • Use atomic molar masses from the periodic table
  • Communicate in g/mol
87
Q

What does the symbol ‘N_A’ represent?

A

Avogadro’s Constant

88
Q

Fill in the blank: Molar mass is measured in _______.

A

g/mol

89
Q

What is the mass of one mole of hydrogen atoms?

A

1.008 g/mol

90
Q

How many peas would cover a large city like New York to a depth of 1 meter?

A

10^15 peas

91
Q

How many peas would cover half of Ontario to a depth of 1 meter?

A

10^18 peas

92
Q

What is the Law of Definite Proportions?

A

A specific compound always contains the same elements in definite proportions by mass.

93
Q

Define quantitative analysis.

A

The process of measuring the quantity of a substance in a sample, providing numerical data.

94
Q

Define qualitative analysis.

A

The process of identifying substances present in a sample, no measurements are involved.

95
Q

What is stoichiometry?

A

The study of the relationships between the quantities of reactants and products involved in chemical reactions.

96
Q

What does the term ‘relative atomic mass’ refer to?

A

The mass of an element that would react with a fixed mass of a standard element, currently Carbon-12.

97
Q

Define atomic mass unit (amu).

A

A unit of mass defined as 1/12 the mass of a carbon-12 atom.

98
Q

What is an isotope?

A

Atoms of an element that have the same number of protons but a different number of neutrons.

99
Q

True or False: Isotopes of an element react chemically in different ways.

A

False.

100
Q

What is isotopic abundance?

A

The percentage of an isotope in a sample of an element.

101
Q

What is the significance of the atomic mass of carbon depicted in the periodic table?

A

It accounts for the naturally occurring isotopes and their relative abundance.

102
Q

Calculate the average atomic mass of chlorine using the isotopes Cl-35 and Cl-37 with their respective abundances.

A

Average atomic mass = (0.7553 * 35) + (0.2447 * 37).

103
Q

Fill in the blank: The only difference between carbon monoxide (CO) and carbon dioxide (CO2) is the ratio of ______ to ______.

A

Carbon to Oxygen.

104
Q

What are the properties of a substance dependent on?

A
  • The quantities of each element
  • The elements the compound is composed of.
105
Q

What is the atomic mass of an isotope calculated by?

A

atomic mass = (% abundance of isotope 1)(mass of isotope 1) + (% abundance of isotope 2)(mass of isotope 2)

106
Q

What was the atomic mass assigned to hydrogen by Dalton?

A

1.

107
Q

Where is Canada’s standard kilogram kept?

A

In a vault at the National Research Council in Ottawa.

108
Q

What is the melting point of carbon monoxide?

A

-199 °C.

109
Q

True or False: Carbon dioxide has a sweet taste.

A

False.

110
Q

What do protons and neutrons represent in atomic structure?

A
  • Protons: Red
  • Neutrons: Blue.

Grade 11 Chemistry (6 decks)

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