Chemical Equation Study Guide
Steps to Balancing A Chemical Equation
1) Determine the number of atoms for each element. 2) Pick an element that is not equal on both sides of the equation. 3) Add a coefficient in front of the formula with that element and adjust your counts. 4) Multiply coefficient and subscript, update atom count 5) Continue adding coefficients to get the same kind and number of atoms of each element on each side.
How many aluminum atoms are there in 2AlBr₃?
2
This formula equation is unbalanced. BaCl2(aq) + Na2CO3(aq)→ BaCO3(s) + NaCl(aq) Which coefficient should be placed in front of NaCl to balance this equation?
2
This formula equation is unbalanced. P4(s) + Cl2(g)→PCl3(l) Which coefficient should be placed in front of PCl3 to balance this equation?
2
The amount of oxygen in the reactants is 4 atoms. In the products, the oxygen is distributed to water (H2O) and O2 gas. Which coefficients would be placed in front of water and oxygen?
2 in front of water and 1 in front of oxygen
hydrogen + nitrogen monoxide yield water + nitrogen
2H₂ + 2NO → 2H₂O + N₂
Potassium Bromide and Magnesium metal are created when Potassium and Magnesium Bromide react.
2K +1MgBr₂ → 2KBr +1Mg
Write the Balanced equation Mg + O2→ MgO?
2Mg + O2 → 2MgO
Sodium Chloride and Fluorine mix to create Sodium Fluoride and Chlorine.
2NaCl + 1F₂ → 2NaF + 1Cl₂
sodium phosphate + calcium chloride yield calcium phosphate + sodium chloride
2Na₃PO₄ + 3CaCl₂ → Ca₃(PO₄)₂ + 6NaCl
Which of the following is a chemical equation that accurately represents what happens when sulfur and oxygen react to form sulfur trioxide?
2S + 3O₂ → 2SO₃
How many sulfur atoms are in Al₂(SO₄)₃?
3
calcium hydroxide + phosphoric acid yield calcium phosphate + water
3Ca(OH)₂ + 2H₃PO₄ → Ca₃(PO₄)₂ + 6H₂O
Write the Balanced Equation NH₄OH + H₃PO₄ → (NH₄)₃PO₄ + H₂O
3NH₄OH + H₃PO₄ → (NH₄)₃PO₄ + 3H₂O
How many oxygen atoms are in C₆H₁₂O₆?
6
Methane (CH₄) burns in oxygen gas to form water and carbon dioxide. What is the correct balanced chemical equation for this reaction?
CH₄ + 2O₂ → 2H₂O + CO₂
Write the Balanced Equation FeCl₃ + NaOH → Fe(OH)₃ + NaCl
FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl
A student balanced the chemical equation Mg + O₂ → MgO by writing Mg + O₂ → MgO₂ Was the equation balanced correctly? Explain your answer. If the equation was not balanced correctly, write the correctly balanced equation.
No. Because it was balanced by changing a subscript instead of changing coefficients.2Mg + O₂ → 2MgO
Write the Balanced equation N₂ + H₂ → NH₃
N₂ + 3H₂ → 2NH₃
Write a balanced equation for the following: Oxygen reacts with hydrogen to yield water.
O + H2 ---> H2O
Iron (III) sulfide (Fe₂S₃) reacts with oxygen to produce iron (III) oxide (Fe₂O₃) and sulfur dioxide (SO₂). Write a balanced chemical equation for this reaction, using the smallest possible whole-number coefficients for the reactants and products.
Since we will be balancing the oxygen last and the iron is already balanced, we will begin by balancing the sulfur atoms. By balancing the sulfur atoms, we have changed the total number of oxygen atoms on the products side to nine. There are nine oxygen atoms on both sides of the reaction, meaning that we have balanced the oxygen atoms.
Consider the following equation: CH₃CH₂OH + O₂ ⟶ 2 CO₂ + 3 H₂O. How many more oxygen molecules are required to balance the chemical equation?
The oxygen atoms are unbalanced. To balance the oxygen atoms, we need to add more oxygen molecules. So, in order to balance the provided chemical equation, two more oxygen molecules are required.
zinc + lead(II)nitrate yield zinc nitrate + lead
Zn + Pb(NO₃)₂ → Zn(NO₃)₂ + Pb
Balanced Chemical Equations
a reaction equation where the number of atoms of each element is the same on the reactant and product sides of the equation.
Is the following chemical equation balanced or unbalanced? H2O + O2 ---> 3O + H2
balanced
What does this symbol (aq) mean?
dissolved in water
Consider the unbalanced equation for the oxidation of butene. C4H8 + 6O2 →CO2 + H2O For each molecule of C4H8 that reacts, how many molecules of carbon dioxide and water are produced?
four carbon dioxide molecules and four water molecules
What does this symbol (g) mean?
gas
What does this symbol (l) mean?
liquid
Stoichiometric Coefficients
numerical values written before a species in a chemical equation in order to balance the overall reaction.
What does this symbol (s) mean?
solid
Which element is out of balance in the chemical equation CH₃CH₂OH + O₂ ⟶ 2CO₂ + 3H₂O?
step 1. Identify the elements as carbon, hydrogen, and oxygen. step 2. With oxygen, our first reactant has one oxygen atom, and our second has two. In our first product, we have four oxygen atoms because we have two CO₂ molecules. Moreover, in our second product, we have three oxygen atoms because we have three water molecules. step 3. Since we do not have the same number of oxygen atoms in the reactants as in the products, oxygen is out of balance. Therefore, the element out of balance in our chemical equation is oxygen.
Is this formula balanced or unbalanced? CO2 + NH3 → OC +H2O
unbalanced
