Chemical Reactions and Equations
Balance the following: Cr(s) + S₈(s) → Cr₂S₃
16 Cr(s) + 3 S₈(s) → 8 Cr₂S₃
Double-replacement reaction
AB + CD →AD + CB reaction in which two different compounds exchange positive ions and form two new compounds
Decomposition Reaction
AX ----> A + X This is a __________ reaction
Balance the following and determine if there is a precipitation reaction occur when:
K₂SO₄(aq) + Pb(NO₃)₂(aq) → PbSO₄(s) + 2 KNO₃(aq)
Write an equation for the reaction that occurs when solutions of potassium sulfate and strontium nitrate are mixed. Does a precipitation reaction occur?
K₂SO₄(aq) + Sr(NO₃)₂(aq) → 2 KNO₃(aq) + SrSO₄(s)
Write a balanced equation for: Solid magnesium reacts with aqueous copper(I) nitrate to form aqueous magnesium nitrate and solid copper.
Mg(s) + 2 CuNO₃(aq) → Mg(NO₃)₂(aq) + 2 Cu(s)
Decomposition reaction
a reaction in which a compound breaks down into two or more simpler substances AB→A + B
Combustion reaction
a reaction in which a substance reacts rapidly with oxygen, often producing heat and light
Single-replacement reaction
a reaction in which one element takes the place of another element in a compound AB + C → CB + A
Synthesis reaction
a reaction in which two or more substances reacts to form a single substance A+B →AB
Write a balanced equation for: Aluminum metal reacts with iron(II) sulfide to form aluminum sulfide and iron metal.
2 Al + 3 FeS → Al₂S₃ + 3 Fe
The reaction between solid chromium(III) oxide and solid carbon produced solid chromium and carbon dioxide gas. The equation for this reaction is:
2 Cr₂O₃(s) + 3 C(s) → 4 Cr(s) + 3 CO₂(g)
Solid iron reacts with aqueous hydrochloric acid to form aqueous iron(III) chloride and hydrogen gas. The equation for this reaction is:
2 Fe(s) + 6 HCl(aq) → 2 FeCl₃(aq) + 3 H₂(g)
Balance the following: H₂O(l) → H₂(g) + O₂(g)
2 H₂O(l) → 2 H₂(g) + O₂(g)
Write an equation for the reaction that occurs when potassium hydroxide and nickel(II) bromide solutions are mixed. Does a precipitation reaction occur?
2 KOH(aq)+NiBr₂(aq) → Ni(OH)₂(s)+2 KBr(aq)
Write a balanced equation for: Gaseous dinitrogen pentoxide decomposes to form nitrogen dioxide and oxygen gas.
2 N₂O₅(g) → 4 NO₂(g) + O₂(g)
Balance this chemical equation: HCl(g) + O₂(g) → H₂O(l) + Cl₂
4 HCl(g) + O₂ → 2 H₂O + 2 Cl₂
During photosynthesis plants use carbon dioxide and water to make glucose and release oxygen. The equation for this reaction is:
6 CO₂ + 6 H2O → C₆H₁₂O₆ + 6O₂
Single Replacement Reaction
A + BX ----> B + AX This is a __________ reaction
Synthesis Reaction
A + X ----> AX This is a __________ reaction
Balance the following and determine if there is a precipitation reaction occur when: Al(NO₃)₃(aq) + KOH(aq) →
Al(NO₃)₃ + 3KOH → Al(OH)₃(s) + 3KNO₃(aq)
Balance: B₂O₃ + HF → BF₃ + H₂O
B₂O₃ + 6 HF → 2 BF₃ + 3 H₂O
When methane (CH₄) is burned on a stove in produces carbon dioxide and water. The equation for this reaction is:
CH₄(g) + 2 O₂(g) → CO₂(g) + 2 H₂O(g)
Balance: CO + H₂ → CH₄ + H₂O
CO + 3 H₂ → CH₄ + H₂O
Write a balanced equation for: Calcium phosphate reacts with sulfuric acid to form calcium sulfate and phosphoric acid.
Ca₃(PO₄)₂ + 3 H₂SO₄ → 3 CaSO₄ + 2 H₃PO₄
Coefficients
Coefficients the numbers that appear before the formula 6 AB (6 is the coefficient.)
AX + BY ---->AY + BX This is a __________ reaction
Double Replacement Reaction
Balance: FeS + HCl → FeCl₂ + H₂S
FeS + 2 HCl → FeCl₂ + H₂S
Write an equation for when sodium carbonate ad copper(II) chloride are mixed. Does a precipitation reaction occur?
Na₂CO₃(aq) + CuCl₂(aq) → 2 NaCl(aq) + CuCO₃(s)
Balance: Na₂S + Cu(NO₃)₂ → NaNO₃ + CuS
Na₂S + Cu(NO₃)₂ → 2 NaNO₃ + CuS
Write a balanced equation for: Solid lead(II) sulfide reacts with aqueous hydrochloric acid to form solid lead(II) chloride and dihydrogen sulfide gas
PbS(s) + 2 HCl(aq) → PbCl₂(s) + H₂S(g)
combustion
Rapid chemical combination of a substance with oxygen, producing water, carbon dioxide, heat and light.
Subscripts
Small numbers placed after a chemical symbol or a formula that indicate the number of atoms of that element present in a chemical reaction. B₁ (1 is the subscript.)
Describe the rules and tips for balancing chemical equations.
Subscripts NEVER hange; coeefixients can be added to balance equations; atoms must be equal on both sides
Write an example of a combustion reaction.
breathing (respiration); a fire; burning sugar; burning gasoline in a car's engine; burning methane
law of conservation of matter
matter can be neither created nor destroyed
List the 5 signs of a chemical reaction.
odor, temperature change, color change, formation of a precipitate (solid), bubbles (gas)
precipitate
solid is formed in product of chemical reaction
