Balancing Chemical Equations

These flashcards cover the key concepts and principles related to balancing chemical equations as discussed in the lecture.

Why is balancing chemical equations important?

Balancing chemical equations ensures the proper amounts of reactants produce the correct amount of products and prevents wastage.

What does the law of conservation of mass state regarding chemical equations?

The total number of atoms of each element must be the same on both sides of the equation; mass cannot be created or destroyed.

What mistake do students often make when balancing equations?

Students often change the subscripts instead of adjusting coefficients to balance the equation.

What is the first step in balancing a chemical equation?

The first step is to translate the word equation into a chemical equation.

How should polyatomic ions be treated when balancing chemical equations?

Polyatomic ions can be treated as a single unit if they appear intact on both sides of the equation.

What should the final form of the coefficients be in a balanced equation?

Coefficients should be in the simplest whole number ratio.

How should coefficients be adjusted when balancing chemical equations?

Coefficients can be adjusted to change the quantity of reactants or products, but should be kept as small as possible.

What concept should be avoided when writing equations?

Using an equal sign; instead, use an arrow to indicate the direction of the reaction.

What should you do if you encounter a molecule with a coefficient of one?

You can omit writing the coefficient of one, as it is typically understood.

Why is it important to balance hydrogen and oxygen last?

Balancing hydrogen and oxygen last helps prevent errors as they are commonly involved in multiple compounds.

What are the starting substances in a chemical reaction called?

The starting substances are called reactants and are written on the left side of the equation.

What are the substances formed by a chemical reaction called?

The result of a chemical reaction is called products, which are written on the right side of the equation.

What indicates the number of atoms of each element present in a single molecule?

The subscript is the small number written to the right of an element symbol that indicates its atom count and cannot be changed during balancing.

What do the symbols (s), (l), (g), and (aq) represent in a chemical equation?

These symbols represent the physical states of the substances: solid, liquid, gas, and aqueous solution.

Which seven elements exist as diatomic molecules (X_{2}) in their natural state?

The diatomic elements are hydrogen (H{2}), nitrogen (N{2}), oxygen (O{2}), fluorine (F{2}), chlorine (Cl{2}), bromine (Br{2}), and iodine (I_{2}).

What does the yield arrow \rightarrow represent?

The yield arrow represents the chemical change occurring and is read as "yields," "produces," or "forms."

What is a skeleton equation?

A chemical equation that provides the chemical formulas of reactants and products but does not yet show the correct relative amounts (unbalanced).

What does "aqueous" (aq) mean in the context of a chemical reaction?

It means the substance is dissolved in water.

How many Oxygen atoms are in the formula unit 3Ca(NO{3}){2}?

There are 18 Oxygen atoms (3\times2\times3=18).

What is the "inventory method" for balancing equations?

A technique where you list and count the number of atoms for each element on the reactant and product sides to ensure they match.

What should you do if you have an odd number of atoms on one side and an even number on the other?

Try doubling all coefficients in the equation to convert the odd count to an even number.

In the term 5H_{2}O, what is the role of the number 5?

It is the coefficient, indicating there are five molecules of water.

Why can you never change the subscript of a chemical formula to help balance?

Changing a subscript changes the substance's chemical identity, which violates the law of conservation of mass.

How is the application of heat typically indicated in a chemical equation?

By placing a Greek letter delta (\Delta) over the yield arrow (\rightarrow).

Where is the chemical symbol for a catalyst placed in a reaction?

It is placed either above or below the yield arrow (\rightarrow) because it is not consumed in the reaction.

What does the Law of Conservation of Atoms ensure in a balanced equation?

It ensures that for every element, the number of atoms on the reactant side equals the number of atoms on the product side.

How is a gas product often indicated in older chemical equations?

By an upward-pointing arrow (\uparrow) next to the chemical formula.

What does the symbol (l) stand for correctly?

It stands for the pure liquid phase of a substance.

What does the symbol (g) stand for correctly?

It stands for the gaseous phase of a substance.

How many Nitrogen atoms are in 2(NH{4}){2}SO_{4}?

There are 4 Nitrogen atoms (2 \times 2 = 4).

What is a "precipitate" in a chemical reaction?

A solid that forms and settles out of a liquid mixture during a chemical reaction, often marked with (s). transition.

What does the symbol \rightleftharpoons signify?

It signifies that the reaction is reversible and occurs in both forward and reverse directions.

Why should you generally balance metals before balancing non-metals?

Balancing metals first often simplifies the process and makes it easier to balance Oxygen and Hydrogen later.

What is the result of multiplying a coefficient by a subscript?

It gives the total number of atoms of that specific element in that part of the chemical equation.

What is the formula for the diatomic element Bromine?

Br_{2}.

What is the formula for the diatomic element Fluorine?

F_{2}.

Balance this skeleton equation: H{2} + Cl{2} \rightarrow HCl.

H{2} + Cl{2} \rightarrow 2HCl.

Balance this equation: Na + Cl_{2} \rightarrow NaCl.

2Na + Cl_{2} \rightarrow 2NaCl.

Balance this decomposition reaction: KClO{3} \rightarrow KCl + O{2}.

2KClO{3} \rightarrow 2KCl + 3O{2}.

Balance this equation: Fe + O{2} \rightarrow Fe{2}O_{3}.

4Fe + 3O{2} \rightarrow 2Fe{2}O_{3}.

Balance this synthesis reaction: H{2}O \rightarrow H{2} + O_{2}.

2H{2}O \rightarrow 2H{2} + O_{2}.

In the equation CH{4} + 2O{2} \rightarrow CO{2} + 2H{2}O, how many Oxygen atoms are on the product side?

There are 4 Oxygen atoms (2 from CO{2} and 2 from 2H{2}O).

If you balance an equation and get coefficients 4, 2, 4, what must you do?

Divide all coefficients by 2 to reach the simplest whole number ratio (2, 1, 2).

Does a chemical equation tell us how fast a reaction happens?

No, it only identifies the substances involved and their relative proportions.

What is the significance of a "closed system" in the Law of Conservation of Mass?

It prevents matter from entering or escaping, allowing the total mass to remain constant throughout the reaction.

How do you recognize a pure diatomic element in a chemical word problem?

Pure elements like "Oxygen gas", "Nitrogen", or "liquid Bromine" must be written as X_{2} in equations.

What is the final step to perform after you think you have balanced an equation?

Recount the atoms of every element on both sides to verify that the totals are exactly equal.

Can a coefficient be a fraction in a final balanced chemical equation?

Generally no; they must be reduced to the lowest whole number ratio.

What is the state of matter symbol for a solid?

(s).

What is the formula for Nitrogen gas?

N_{2} (diatomic).