WorksheetsChemistry Concepts: Moles and Limiting Reactants
Total questions: 23
Worksheet time: 12mins
How many formula units are in a given number of moles?
6.022 x 10^23 formula units per mole
3.011 x 10^23 formula units per mole
1.204 x 10^24 formula units per mole
None of the above
How to convert mass (grams) to moles?
By dividing the mass by the molar mass
By multiplying the mass by the molar mass
By adding the mass to the molar mass
By subtracting the molar mass from the mass
How to find the amount of product produced in a reaction given the reactants? For a chemical reaction like: Fe2+(aq) + 2 SCN−(aq) → Fe(SCN)2(s), this equation tells you that: 1 mole of Fe2+ reacts with 2 moles of SCN− to form 1 mole of Fe(SCN)2.
By using stoichiometry to calculate the moles of product from the moles of reactants.
By measuring the temperature change in the reaction.
By observing the color change in the reaction.
By calculating the pH of the solution.
Avogadro's number is used to:
determine the number of atoms or molecules in a mole of a substance
measure the volume of a gas at standard temperature and pressure
calculate the energy of a photon
find the pH of a solution
The mass of one mole of a substance is called:
Molar mass
Atomic mass
Molecular weight
Avogadro's number
Which of the following is used to convert between grams and moles?
Avogadro's number
Molar Mass
Stoichiometry
Limiting Reactant
Complete, Balance, and Identify the Equations: a. Molecular Equation - The molecular equation shows the complete compounds in their undissolved state or as they appear in solution without breaking them into ions. Example formula: 2 NaCl (aq)+Pb(NO3)2(aq)→PbCl2(s)+2 NaNO3(aq)2NaCl (aq)+Pb(NO3)2(aq)→PbCl2(s)+2NaNO3(aq). Explanation: In this molecular equation, we write the reactants and products as whole compounds. (aq) means the substance is dissolved in water, and (s) means it is a solid (precipitate).
What is the state of NaCl in the molecular equation?
What is the state of PbCl2 in the molecular equation?
What is the state of NaNO3 in the molecular equation?
What is the state of Pb(NO3)2 in the molecular equation?
Complete, Balance, and Identify the Equations: b. Total Ionic Equation - The total ionic equation shows all the ions that are present in the solution, where soluble compounds are broken into their respective ions. Example: 2 Li+(aq)+SO42−(aq)+Sr2+(aq)+2 Cl−(aq)→2 Li+(aq)+2 Cl−(aq)+SrSO4(s)2Li+(aq)+SO42−(aq)+Sr2+(aq)+2Cl−(aq)→2Li+(aq)+2Cl−(aq)+SrSO4(s). Explanation: (aq) is for aqueous, meaning the ions are dissolved in the solution. We show all the ions involved in the reaction, not just the compounds.
The total ionic equation shows all the ions present in the solution.
The total ionic equation shows only the compounds involved in the reaction.
The total ionic equation does not include aqueous ions.
The total ionic equation is the same as the molecular equation.
Balance the Reaction and Identify Precipitate: To balance the equation, we need to make sure that the number of atoms of each element is the same on both sides. This will give us a balanced equation. For the equation:
Balance the Reaction and Identify Precipitate
Identify the Catalyst and Balance the Reaction
Determine the Limiting Reactant and Balance the Reaction
Calculate the Molar Mass and Balance the Reaction
The importance of balancing atoms in the reaction: Fe2(SO4)3(aq) + 3 Ba(NO3)2(aq) → 2 Fe(NO3)3(aq) + 3 BaSO4(s) is to:
ensure the conservation of mass.
increase the reaction rate.
produce more products.
change the state of reactants.
What are oxidation numbers and how do they help in understanding electron transfer in reactions?
Oxidation numbers are theoretical charges assigned to atoms, helping to track electron transfer in reactions.
Oxidation numbers are the actual charges on ions, used to balance chemical equations.
Oxidation numbers are the number of electrons in an atom, used to determine its reactivity.
Oxidation numbers are the number of protons in an atom, used to identify elements.
In a redox reaction, where do electrons go and what happens during oxidation and reduction?
Electrons are transferred to the oxidizing agent; oxidation involves loss of electrons and reduction involves gain of electrons.
Electrons are transferred to the reducing agent; oxidation involves gain of electrons and reduction involves loss of electrons.
Electrons remain with the oxidizing agent; oxidation involves gain of electrons and reduction involves loss of electrons.
Electrons remain with the reducing agent; oxidation involves loss of electrons and reduction involves gain of electrons.
What is an oxidizing agent?
A substance that donates electrons
A substance that accepts electrons
A substance that neither donates nor accepts electrons
A substance that only donates protons
In the reaction ClO3−→ClO2−, what type of agent is needed to donate electrons?
Oxidizing agent
Reducing agent
Catalyst
Inert gas
Explain the steps to calculate the empirical formula from percentage composition.
Determine the mass of each element in 100 grams of the compound, convert the masses to moles, divide by the smallest number of moles to get the ratio, and write the empirical formula.
Convert the percentage to a fraction, multiply by Avogadro's number, and write the molecular formula.
Use the periodic table to find the atomic number, divide by the percentage, and write the empirical formula.
Find the molecular weight, divide by the percentage composition, and write the empirical formula.
What is the empirical formula based on the given mole ratio of Hydrogen and Oxygen?
H2O
H2O2
HO
H3O
How do you find the molecular formula once you have the empirical formula?
By multiplying the empirical formula by a whole number
By adding more atoms to the empirical formula
By dividing the empirical formula by a whole number
By rearranging the atoms in the empirical formula
If the empirical formula mass is 90 g/mol, and the molecular mass is 300 g/mol, what is the molecular formula?
C3H6O3
C6H12O6
C9H18O9
C10H20O10
What does a molecular equation show?
The complete chemical formulas of reactants and products
Only the ions involved in the reaction
The net ionic equation
The physical states of the reactants and products
What does a total ionic equation show?
The ions present in a chemical reaction
The products of a chemical reaction
The reactants of a chemical reaction
The energy change in a chemical reaction
What does a net ionic equation show?
The ions that participate in a chemical reaction
The complete formula of all reactants and products
The physical states of the reactants and products
The energy change during the reaction
What is oxidation?
A chemical reaction involving the loss of electrons
A process of gaining electrons
A type of physical change
A method of separating mixtures
What is the role of a reducing agent?
To donate electrons
To accept electrons
To increase oxidation state
To act as a catalyst
