Chapter Flashcards
What do the coefficients in a chemical reaction specify?
The relative amounts in moles of each of the substances involved in the reaction
Coefficients indicate the ratio of reactants and products in a balanced chemical equation.
In the balanced equation 2 C8H18 + 25 O2 → 16 CO2 + 18 H2O, how many molecules of CO2 are produced from 2 molecules of C8H18?
16 molecules of CO2
This reflects the stoichiometric ratio from the balanced equation.
What is the first step in balancing a chemical equation?
Write a skeletal equation by writing chemical formulas for each of the reactants and products
A skeletal equation serves as the starting point for balancing.
When balancing chemical equations, which ions should be balanced second?
Nonmetal ions (anions)
If a polyatomic anion exists on both sides, balance it as a unit.
Fill in the blank: The stoichiometric ratio acts as a ______ between the amount in moles of a reactant to moles of a product.
conversion factor
What is the stoichiometric ratio of C8H18 to CO2 in the combustion reaction?
2 moles C8H18 : 16 moles CO2
This ratio is derived from the balanced equation.
How many moles of CO2 are produced when 22.0 moles of C8H18 are combusted?
176 moles of CO2
Calculation based on the stoichiometric ratio.
What is the mass of CO2 produced when 3.6 × 10^15 grams of C8H18 is burned?
1.1 × 10^16 grams of CO2
This is determined through mole-to-mass conversion using stoichiometric ratios.
What should be done if the balanced equation contains coefficient fractions?
Clear these by multiplying the entire equation by the denominator of the fraction
This ensures whole number coefficients for clarity.
When balancing a chemical equation, which type of atoms should be balanced last?
Free elements
Always adjust the coefficient on the free element to balance.
True or False: In a balanced equation, the total number of each type of atom on both sides must be the same.
True
List the steps for balancing chemical equations.
- Write a skeletal equation
- Balance metal ions first
- Balance nonmetal ions second
- Balance free elements last
- Clear coefficient fractions if necessary
- Check the balance
Following these steps ensures a systematic approach to balancing equations.
What is the balanced equation for the combustion of butane (C4H10) with oxygen?
C4H10 + O2 → CO2 + H2O
This skeletal equation needs to be balanced through the steps outlined.
What is the balanced equation for the combustion of butane (C4H10)?
C4H10(g) + 5 O2(g) → 4 CO2(g) + 5 H2O(g)
This equation shows butane reacting with oxygen to produce carbon dioxide and water.
What defines a chemical change?
Changes that alter the composition of matter
During a chemical change, atoms rearrange to form new substances.
Give an example of a chemical change.
Rusting of iron
Rust occurs when iron reacts with oxygen, forming iron(III) oxide (Fe2O3).
What is a physical change?
Changes that alter only the state or appearance without changing composition
Example: Water boiling to become steam.
What is the average rise in atmospheric temperature since 1860?
0.8 °C (1.4 °F)
This temperature change coincides with a 37% rise in atmospheric CO2 levels.
What are greenhouse gases?
Gases that allow sunlight in, warm the Earth’s surface, and prevent heat from escaping
They play a crucial role in the greenhouse effect.
What is stoichiometry?
The study of the numerical relationship between chemical quantities in a chemical reaction
It involves balancing chemical equations and calculating reactants and products.
What is a limiting reactant?
The reactant that is completely consumed in a reaction
It determines the maximum amount of product that can be formed.
What is the theoretical yield?
The maximum amount of product that can be formed from the limiting reactant
It is calculated based on stoichiometry.
What is a physical change?
Changes that alter only the state or appearance, but not the composition
The identity of the substance remains the same.
Fill in the blank: A _____ change results in a new substance being formed.
chemical
Fill in the blank: In reactions involving multiple reactants, the reactant that limits the amount of product is called the _____ reactant.
limiting
True or False: The balance between incoming and outgoing energy from the sun determines Earth’s average temperature.
True
What are the states of matter indicated in chemical equations?
Gas (g), liquid (l), solid (s), aqueous (aq)
These states describe the physical form of reactants and products.
What is the first step in balancing chemical equations?
Write a skeletal (unbalanced) equation
This involves writing chemical formulas for each of the reactants and products.
What happens if the balanced equation contains coefficient fractions?
Multiply the entire equation by the denominator of the fraction
This clears the fractions and helps in balancing.
What is the importance of confirming that a chemical equation is balanced?
To ensure the law of conservation of mass is upheld
The number of atoms of each element must be the same on both sides of the equation.
What is the role of halogens in chemical reactions?
They form 1- anions and react with metals to create ionic compounds
Example: Halogens react with hydrogen to produce hydrogen halides.
What is the relationship between moles of carbon dioxide and glucose in photosynthesis?
1 mole of glucose is produced from 6 moles of carbon dioxide
The balanced equation for photosynthesis is 6 CO2(g) + 6 H2O(l) → 6 O2(g) + C6H12O6(aq).
Fill in the blank: The reactant in excess is any reactant that occurs in a quantity greater than is required to completely react with the _____ reactant.
limiting
What does the term ‘percent yield’ refer to?
The ratio of the actual yield to the theoretical yield, expressed as a percentage
It indicates the efficiency of a reaction.
What is the molar mass of carbon (C)?
12.01 g/mol
What is the molar mass of titanium dioxide (TiO2)?
79.87 g/mol
In the reaction of Fe2O3 and CO, which reactant is the limiting reactant?
CO
What is the balanced equation for the reaction of potassium and bromine?
2 K(s) + Br2(g) → 2 KBr(s)
What products are formed when alkali metals react with water?
- Dissolved alkali metal ion
- Hydroxide ion
- Hydrogen gas
What is a combustion reaction?
A reaction involving a substance reacting with O2 to form oxygen-containing compounds.
What is produced in the combustion of methane?
- CO2(g)
- H2O(g)
- Heat
What is the molar mass of carbon dioxide (CO2)?
44.01 g/mol
What is the theoretical yield of ammonia (NH3) when NO is the limiting reactant?
49.0 g
What is the balanced equation for the formation of sulfuric acid (H2SO4) from sulfur dioxide (SO2)?
2 SO2(g) + O2(g) + 2 H2O(l) → 2 H2SO4(aq)
What is the molar mass of sulfuric acid (H2SO4)?
98.09 g/mol
What is the limiting reactant in the reaction of titanium dioxide (TiO2) and carbon (C) if 28.6 kg C reacts with 88.2 kg TiO2?
To be determined based on stoichiometric calculations
What is the percent yield if 42.8 kg of titanium is produced from the reaction of TiO2 and C?
To be calculated based on theoretical yield vs actual yield
Fill in the blank: The reaction of alkali metals with halogens typically forms ______.
[metal halide]
True or False: The reaction of alkali metals with water is typically non-exothermic.
False
What is the balanced equation for the complete combustion of methanol (CH3OH)?
2 CH3OH(l) + 3 O2(g) → 2 CO2(g) + 4 H2O(g)
What is the main product of the combustion of organic substances?
CO2 and H2O
What are the products of the reaction between nitrogen gas (N2) and hydrogen gas (H2) to form ammonia (NH3)?
2 NH3(g)
In stoichiometry, what is the first step when given a mass of a reactant?
Convert mass to moles using molar mass.
What is the relationship used to convert from grams of SO2 to grams of H2SO4?
2 mol SO2 : 2 mol H2SO4 from the balanced equation
How many pizzas can be made if you have enough crusts for 4, cheese for 5, but only enough tomato sauce for 3?
3 pizzas
What is the limiting reactant in a chemical reaction?
The reactant that is completely consumed and limits the amount of product.
In the pizza analogy, which ingredient is the limiting reactant?
Tomato sauce
What is the actual yield in a chemical reaction?
The amount of product actually produced.
What is the theoretical yield in a chemical reaction?
The amount of product that can be made based on the limiting reactant.
How is percent yield calculated?
Percent yield = (actual yield / theoretical yield) x 100
Fill in the blank: The maximum number of pizzas that can be made depends on the _______.
[limiting reactant]
What are the molar masses of NO and H2?
NO = 30.01 g/mol; H2 = 2.02 g/mol
What does the term ‘reactant in excess’ refer to?
Any reactant that occurs in a quantity greater than required to completely react with the limiting reactant.
True or False: The theoretical yield is always equal to the actual yield.
False
What is the significance of the limiting reactant in stoichiometry?
It determines the maximum amount of product that can be formed.
What is the relationship between moles and grams in stoichiometry?
Moles can be converted to grams using molar mass.
Fill in the blank: The reactant that makes the least amount of product is called the _______.
[limiting reactant]
What is the role of stoichiometric relationships in determining theoretical yield?
They convert between moles of reactant and moles of product.
