$CATEGORY: Science - Khan Academy/1.Chemical Reactions and Equations/1.Chemical Reactions and Equations--Chemical Equations

//Multiple Choice

What is the primary goal when balancing a chemical equation? {
    ~To ensure the total mass of the reactants equals the total mass of the products
    =To make the number of atoms on both sides equal
    ~To increase the number of molecules in the reaction
    ~To balance only the metals involved in the reaction
}

What is the chemical equation for the reaction between aluminum and dioxygen? {
    ~\(Al + O \= AlO\)
    =\(Al + O_2 \= Al_2O_3\)
    ~\(2Al + O_2 \= Al_2O_3\)
    ~\(Al_2 + O_2 \= Al_2O_2\)
}

How many oxygen atoms are there on the left-hand side of the equation \(Al + O_2 \= Al_2O_3\)? {
    ~1
    =2
    ~3
    ~6
}

Which of the following is a valid representation of the balanced equation for the reaction of aluminum and dioxygen? {
    =\(4Al + 3O_2 \= 2Al_2O_3\)
    ~\(2Al + 3O_2 \= Al_2O_3\)
    ~\(4Al + O_2 \= 3Al_2O_3\)
    ~\(4Al + 2O_2 \= 2Al_2O_3\)
}

What would you multiply both sides by to eliminate a fractional coefficient in balancing a chemical equation? {
    =A number that makes the coefficient an integer
    ~A number that makes the reactants equal to the products
    ~The atomic number of an element
    ~A constant to balance the heat energy
}

What does a balanced chemical equation ensure in terms of atoms? {
    =The number of atoms of each element is the same on both sides
    ~It shows the temperature at which a reaction happens
    ~It shows the amount of energy released
    ~It only balances the number of molecules
}

//True or False

The chemical equation \(Al + O_2 \= Al_2O_3\) is already balanced. {F}

The number of atoms on the left-hand side should equal the number of atoms on the right-hand side in a balanced equation. {T}

Multiplying both sides of the chemical equation by 2 helps eliminate fractional coefficients. {T}

In the balanced equation \(4Al + 3O_2 \= 2Al_2O_3\), the number of aluminum atoms on both sides is the same. {T}

It is acceptable to have fractional coefficients when balancing chemical equations. {F}

The equation \(Al + O_2 \= Al_2O_3\) involves the reaction of aluminium with oxygen. {T}

To balance the number of oxygen atoms in the equation \(Al + O_2 \= Al_2O_3\), you can multiply by 1.5 on the LHS. {T}

A chemical equation is balanced when there are more products than reactants. {F}

Aluminium oxide \(Al_2O_3\) contains 2 aluminium atoms and 3 oxygen atoms. {T}

The number of molecules in a chemical equation must always be balanced, regardless of the atoms. {F}

A balanced equation involves adjusting the coefficients of the chemical substances involved. {T}

The reaction \(4Fe + 3O_2 \= 2Fe_2O_3\) is an example of a balanced equation. {T}

//Fill in the blanks

The equation \(Al + O_2 \= Al_2O_3\) describes a reaction between aluminium and ___________. {
    ~Nitrogen
    =Oxygen
    ~Hydrogen
}

The product of the reaction between aluminum and dioxygen is ___________. {
    =Aluminum oxide
    ~Aluminum chloride
    ~Aluminium sulphate
}

To balance the equation \(Al + O_2 \= Al_2O_3\), the number of __________ atoms on both sides must be equal. {
    =Aluminium
    ~Nitrogen
    ~Hydrogen
}

The number of __________ on the left-hand side of the equation must equal the number on the right-hand side. {
    =Atoms
    ~Molecules
    ~Electrons
}

In the equation \(Al + O_2 \= Al_2O_3\), oxygen molecules consist of __________ oxygen atoms. {
    ~1
    =2
    ~3
}

In the balanced equation, you need __________ molecules of dioxygen to react with aluminum. {
    ~1
    ~2
    =3
}

To eliminate fractional coefficients, you would multiply both sides of the equation by __________. {
    ~1
    =2
    ~3
}

The balanced form of the equation \(Al + O_2 \= Al_2O_3\) is __\(Al + 3O_2 \= 2Al_2O_3\). {
    ~1
    ~2
    =4
}

The equation \(Al + O_2 \= Al_2O_3\) is a chemical __________. {
    ~Bond
    =Reaction
    ~Process
}

To balance oxygen in the equation, we need __________ oxygen molecules. {
    ~2
    =3
    ~1
}

The coefficient in front of oxygen when the equation is balanced is __________. {
    ~1
    =3
    ~2
}

After balancing the equation, the total number of oxygen atoms on the left equals __________ oxygen atoms on the right. {
    ~2
    ~4
    =6
}

In balancing chemical equations, you adjust the __________ of the molecules. {
    ~Temperature
    ~Volume
    =Coefficients
}

The equation for the reaction of aluminum with oxygen is an example of a __________ reaction. {
    ~Decomposition
    =Synthesis
    ~Single displacement
}

//Numericals



//Match the following

Match the following items from Column A with their correct corresponding options from Column B\:
{
=2KClO3 \= 2KCl + 3O2 -> Balanced Equation
=2Al + 3Br2 \= 2AlBr3 -> 6 Bromine atoms on either side
=CaO -> Calcium Oxide
=C2H6 + O2 \= CO2 + H2O -> Unbalanced Equation
=Aluminium oxide -> 2 aluminium atoms
}


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