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

//Multiple Choice

Which of the following represents the initial unbalanced chemical equation for the combustion of ethylene? {
    ~\(C_2H_4\) (g) + \(2O_2\) (g) \= \(CO_2\) (g) + \(H_2O\) (l)
    =\(C_2H_4\) (g) + \(O_2\) (g) \= \(CO_2\) (g) + \(H_2O\) (l)
    ~\(C_2H_4\) (g) + \(3O_2\) (g) \= \(2CO_2\) (g) + \(2H_2O\) (l)
    ~\(C_2H_4\) (g) + \(O_2\) (g) \= \(2CO_2\) (g) + \(2H_2O\) (l)
}

What is the first element balanced in the chemical equation? {
    ~Hydrogen
    ~Oxygen
    =Carbon
    ~Ethylene
}

After balancing the carbons, how many molecules of \(CO_2\) are on the right-hand side of the equation? {
    ~1
    =2
    ~3
    ~4
}

Which of the following molecules is balanced by adjusting the number of water molecules in the equation? {
    ~Oxygen
    ~Carbon
    =Hydrogen
    ~Nitrogen
}

What is the total number of oxygen atoms on the right-hand side after balancing the equation? {
    ~4
    =6
    ~8
    ~10
}

Which of the following is the final balanced equation? {
    ~\(C_2H_4\) (g) + \(O_2\) (g) \= \(CO_2\) (g) + \(H_2O\) (l)
    ~\(C_2H_4\) (g) + \(2O_2\) (g) \= \(2CO_2\) (g) + \(2H_2O\) (l)
    =\(C_2H_4\) (g) + \(3O_2\) (g) \= \(2CO_2\) (g) + \(2H_2O\) (l)
    ~\(C_2H_4\) (g) + \(3O_2\) (g) \= \(CO_2\) (g) + \(H_2O\) (l)
}

What is the total number of oxygen atoms on the left-hand side of the final balanced equation? {
    =6
    ~8
    ~10
    ~12
}

What does the "g" in parentheses next to \(C_2H_4\) (g) represent? {
    =Gas form
    ~Solid form
    ~Liquid form
    ~Gas molecule
}

Which molecule is considered the single element molecule in the balanced chemical equation? {
    ~Ethylene \((C_2H_4\))
    =Oxygen \((O_2)\)
    ~Carbon dioxide \((CO_2)\)
    ~Water \((H_2O)\)
}

//True or False

The initial equation for the combustion reaction of ethylene is balanced. {F}

Balancing oxygen is done before balancing hydrogen in a combustion reaction. {F}

The number of hydrogen atoms is balanced by adjusting the number of water molecules. {T}

The unbalanced equation has 2 oxygen atoms on the left-hand side. {T}

There are 2 oxygen molecules on the right-hand side in the unbalanced equation. {F}

Balancing the carbons first makes the rest of the balancing process easier. {T}

In the final balanced equation, the number of oxygen molecules on the left-hand side is 6. {F}

The molecule dioxygen \(O_2\) is used to balance the oxygen atoms. {T}

The final equation has 4 hydrogen atoms on both sides. {T}

In the balanced equation, two molecules of water are needed to balance hydrogen. {T}

//Fill in the blanks

The initial chemical equation for the combustion of ethylene is\: \(C_2H_4\) (g) + _____(g) \= \(CO_2\) (g) + \(H_2O\) (l). {
    =\(O_2\)
    ~\(H_2\)
    ~\(N_2\)
    ~\(CO_2\)
}

The number of hydrogen atoms on the left-hand side of the initial chemical equation for the combustion of ethylene is _______. {
    ~2
    =4
    ~6
    ~8
}

To balance hydrogen, the number of H2O molecules is increased to _______. {
    ~1
    =2
    ~3
    ~4
}

The number of oxygen molecules needed on the left-hand side to balance the equation is _______. {
    ~1
    ~2
    =3
    ~4
}

The number of carbons in the final balanced equation is _______. {
    ~1
    =2
    ~3
    ~4
}

The number of water molecules used to balance the hydrogens is _______. {
    ~1
    =2
    ~3
    ~4
}

The final balanced equation is \(C_2H_4\) (g) + \(3O_2\) (g) \= \(2CO_2\) (g) + \(2\)_____ (l). {
    ~\(CO_2\)
    =\(H_2O\)
    ~\(H_2\)
    ~\(O_2\)
}

The number of hydrogen atoms on the left-hand side is _______. {
    ~2
    =4
    ~6
    ~8
}

_______ is balanced last in the combustion reaction because it involves single element molecule. {
    =Oxygen
    ~Nitrogen
    ~Hydrogen
    ~Carbon
}

The unbalanced equation for the combustion of ethylene starts with _______ oxygen molecule(s). {
    =1
    ~2
    ~3
    ~4
}

The "l" in the chemical formula \(H_2O\) (l) represents that the molecule is in _______ form. {
    ~Solid
    =Liquid
    ~Gas
    ~Plasma
}

The number of molecules of oxygen needed for the combustion reaction to be balanced is _______. {
    ~1
    ~2
    =3
    ~4
}

//Numericals



//Match the following

Match the following items from Column A with their correct corresponding options from Column B\:
{
=Ethylene -> C2H4
=Oxygen Molecule -> O2
=Combustion Reaction -> C2H4 (g) + 3O2 (g) \= 2CO2 (g) + 2H2O (l)
=First balance -> Molecules with multiple elements
}


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