Writing and Balancing Chemical Equations Quiz: Learn to Write Balanced Equations

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Questions and Answers

What is the advantage of using chemical formulae in chemical equations?

It is not necessary to use chemical formulae
It makes the equation more difficult to understand
It makes the equation more concise and useful (correct)
It makes the equation more lengthy

What is the purpose of the arrow in a word-equation?

To show the direction of the reaction (correct)
To indicate the reactants and products are the same
To balance the chemical equation
To separate the reactants and products

What does a word-equation show?

The chemical properties of the reactants
The change of reactants to products (correct)
The chemical properties of the products
The chemical formulae of the reactants and products

What is the condition for a chemical equation to be balanced?

The number of atoms of each element is the same on both sides of the equation (D) Signup and view all the answers

What is the significance of the plus sign (+) in a word-equation?

It indicates the presence of multiple reactants or products (A) Signup and view all the answers

What is the difference between a word-equation and a chemical equation?

A word-equation uses words while a chemical equation uses chemical formulae (D) Signup and view all the answers

What is the purpose of writing the notation (aq) in a chemical equation?

To indicate the reactant or product is present as a solution in water (A) Signup and view all the answers

Why are physical states not always included in a chemical equation?

Because they are only necessary to specify when it is important to know (C) Signup and view all the answers

What is the symbol (g) used to indicate in a chemical equation?

That the reactant or product is present as a gas (A) Signup and view all the answers

Where are the reaction conditions, such as temperature, pressure, and catalyst, usually indicated in a chemical equation?

Above and/or below the arrow in the equation (A) Signup and view all the answers

What is the purpose of cleaning a magnesium ribbon before burning in air?

To remove any impurities that may affect the reaction (D) Signup and view all the answers

What is the purpose of balancing a chemical equation?

To ensure that the total mass of elements is the same before and after a chemical reaction (C) Signup and view all the answers

What is the purpose of balancing a chemical equation?

To ensure the number of atoms of each element is the same on both reactant and product sides (C) Signup and view all the answers

What is the difference between a skeletal chemical equation and a balanced chemical equation?

A skeletal chemical equation is an unbalanced equation, while a balanced chemical equation is a equation with equal atoms of each element on both sides (A) Signup and view all the answers

What is the correct step to balance the chemical equation Fe + H2O → Fe3O4 + H2?

First, draw boxes around each formula (D) Signup and view all the answers

What is the purpose of the arrow in a chemical equation?

To separate the reactants and products in a chemical reaction (C) Signup and view all the answers

What is the result of a balanced chemical equation?

The number of atoms of each element is the same on both sides (C) Signup and view all the answers

What is the representation of the word-equation 'Zinc + Sulphuric acid → Zinc sulphate + Hydrogen' in a chemical equation?

Zn + H2SO4 → ZnSO4 + H2 (B) Signup and view all the answers

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Study Notes

Representing Chemical Reactions

A word-equation is a simple way to represent a chemical reaction, where reactants are written on the left-hand side (LHS) with a plus sign (+) between them, and products are written on the right-hand side (RHS) with a plus sign (+) between them.
The arrowhead points towards the products, showing the direction of the reaction.

Chemical Equations

A chemical equation represents a chemical reaction and can be made more concise by using chemical formulae instead of words.
A chemical equation can be unbalanced, meaning the number of atoms of each element on the LHS and RHS of the arrow is not the same.
A balanced chemical equation is one where the number of atoms of each element remains the same on both the LHS and RHS.

Balancing Chemical Equations

The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction.
To balance a chemical equation, count and compare the number of atoms of each element on the LHS and RHS of the arrow.
Steps to balance a chemical equation: draw boxes around each formula, identify the elements, and balance the equation.

Examples of Chemical Equations

Zn + H2SO4 → ZnSO4 + H2 is a balanced chemical equation.
3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g) is a balanced chemical equation.

Notations in Chemical Equations

(g), (l), (aq), and (s) represent the gaseous, liquid, aqueous, and solid states of reactants and products, respectively.
Physical states are not always included in a chemical equation, unless necessary to specify them.
Reaction conditions, such as temperature, pressure, and catalyst, can be indicated above and/or below the arrow in the equation.