Chemistry Test Reactions
In a chemical equation, the formula of a substance in water solution is followed by the symbol
(aq)
In an equation, the symbol for a substance in water solution is followed by
(aq)
The formation of a solid product in a chemical reaction is represented by the symbol
(s)
Which coefficients correctly balance the formula equation CaO + H2O → Ca(OH)2?
1, 1, 1
Which coefficients correctly balance the formula equation NH4NO2(s)→ N2(g) + H2O(l)?
1, 1, 2
Which set of coefficients will balance the equation below? NaOH + Cu(NO3)2 Cu(OH)2 + NaNO3
2, 1, 1, 2
Which coefficients correctly balance the formula equation below? KClO3(s) KCl(s) + O2(g)
2, 2, 3
AgNO3 + CuCl2 -> AgCl + Cu(NO3)2
2AgNO3 + CuCl2 -> 2AgCl + Cu(NO3)2
What is the balanced equation when aluminum reacts with copper(II) sulfate?
2Al + 3CuSO4 → Al2(SO4)3 + 3Cu
Which equation is not balanced?
2H2 + O2 --> H2O
Which equation is not balanced?
2H2 + O2 → H2O
Which of the following equations represents a decomposition reaction?
2HgO(s) 2Hg(l) + O2(g)
PbO2 -> PbO + O2
2PbO2 -> 2PbO + O2
When the formula equation CuSO4(aq) + Fe(s) → Fe2(SO4)3(aq) + Cu(s) is correctly balanced, the coefficient of CuSO4(aq) is
3
What is the total number of molecules represented by the following equation? 2C4H10(g) + 13O2(g) 8CO2(g) + 10H2O(g)
33
What is the total number of molecules that is represented by the following chemical equation? NH4NO2 -> N2 + 2H2O
4
Which of the following equations represents the balanced equation for the reaction of iron and oxygen?
4Fe + 3O2 -> 2Fe2O3
When the equation Fe3O4 + Al → Al2O3 + Fe is correctly balanced, what is the coefficient of Fe?
9
Which of the following may indicate that a chemical reaction has occurred?
All of the above
Which of the following is a formula equation for the formation of carbon dioxide from carbon and oxygen?
C + O2 → CO2
The word equation solid carbon + oxygen gas → carbon dioxide gas + energy, represents a chemical reaction because
CO2 has chemical properties that differ from those of C and O
Calcium carbonate -> calcium oxide + carbon dioxide
CaCO3 -> CaO + CO2
Predict what happens when calcium metal is added to a solution of magnesium chloride
Calcium Chloride forms
Cl2(g) + MgBr2(aq) ->
Cl2(g) + MgBr2(aq) -> MgCl2(aq) + Br2(l)
A mixture of propane and oxygen react to form carbon dioxide and water. What type of chemical reaction is this?
Combustion
Write a balanced chemical equation for the following reaction: iron plus copper(I) nitrate yields iron(II) nitrate plus copper
Fe(s) + 2CuNO3(aq) → Fe(NO3)2(aq) + 2Cu(s)
Which of the following equations represents a double-displacement reaction?
FeS(s) + 2HCl(aq) -> H2S(g) + FeCl2(aq)
In the reaction Zn(s) + H2SO4(aq) ZnSO4(aq) + H2(g), what element has been displaced?
H
In writing a chemical equation that produces hydrogen gas, the correct representation of hydrogen gas is
H2
In writing a formula equation for a reaction that produces hydrogen gas, the correct representation of hydrogen gas is
H2(g)
Predict what happens when lead is added to nitric acid
Hydrogen is released
Which word equation represents the reaction that produces water from hydrogen and oxygen?
Hydrogen plus oxygen yields water
Which of the following is true regarding the law of conservation of mass?
It dictates that the number of atoms of each element must be the same on both sides of a chemical equation
Which of the following is not true regarding a properly written chemical equation?
It must show the formation of a precipitate or a gas
Which equation below violates the law of conservation of mass?
KCl + Br2 -> KBr + Cl2
Magnesium + Oxygen --> Magnesium oxide
Mg + O2 --> MgO
In the chemical equation 2Mg(s) + O2(g) → 2MgO(s),
Mg represents the reagent magnesium
Mg(s) + Co(NO3)2(aq) ->
Mg(s) + Co(NO3)2(aq) Mg(NO3)2(aq) + Co(s)
Predict the product of the reaction represented by the following equation: MgO + CO2 →
MgCO3
Magnesium bromide (aq) + chlorine (g) yields
MgCl2(aq) and Br2(l)
The formulas for the products of the reaction between sodium hydroxide and sulfuric acid are
Na2SO4 and H2O
In the word equation, sodium oxide + water → sodium hydroxide, the formula for sodium hydroxide is represented by
NaOH
Ni(s) + CuCl2(aq) ->
Ni(s) + CuCl2(aq) -> NiCl2(aq) + Cu(s)
How would oxygen be represented in the formula equation for the reaction of methane and oxygen to yield carbon dioxide and water?
O2
Which of the following is true regarding single-displacement reactions?
One element replaces another in a compound
Write a balanced chemical equation for the synthesis of liquid phosphorus trichloride, PCl3, from white phosphorus, P4, and chlorine gas
P4(s) + 6Cl2(g) → 4PCl3(l)
What is the balanced equation for the combustion of sulfur?
S(s) + O2(g) → SO2(g)
You mix solution A with solution B in a beaker. Which of the following observations does not help you prove that a chemical reaction has occurred?
Solution A, solution B, and the mixture are all yellow
CaO(s) + H2O(l) Ca(OH)2(s)
Synthesis reaction
Which of the following indicates that a chemical equation is balanced?
The numbers of atoms of each element are the same on both sides of the equation
Which of the following is true regarding double-displacement reactions?
Two products are formed, the ions of the two reactants must be exchanged, and a precipitate may form
Zn(OH)2 + CH3COOH -> Zn(CH3COO)2 + H2O
Zn(OH)2 + 2CH3COOH Zn(CH3COO)2 + 2H2O
The complete balanced equation for the reaction between zinc hydroxide and acetic acid is
Zn(OH)2 + 2CH3COOH → Zn(CH3COO)2 + 2H2O
Zn(s) + HCl(aq) ->
Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)
What is the small whole number that appears in front of a formula in a chemical equation?
a coefficient
In the expression 3CO2, the numbers 3 and 2 are, respectively
a coefficient and a subscript
When a solid produced by a chemical reaction separates from the solution it is called
a precipitate
To balance a chemical equation, you must
adjust the coefficients
After the first steps in writing an equation, the equation is balanced by
adjusting coefficients to the smallest whole-number ratio
In the equation 2Al(s) + 3Fe(NO3)2(aq) → 3Fe(s) + 2Al(NO3)3(aq), iron has been replaced by
aluminum
According to the law of conservation of mass, the total mass of the reacting substances is
always equal to the total mass of the products
An insoluble gas that forms in a double-displacement reaction in aqueous solution
bubbles out of solution
The reaction of calcium oxide, CaO, with water yields
calcium hydroxide
When heated, a metal carbonate decomposes into a metal oxide and
carbon dioxide
Which observation does not indicate that a chemical reaction has occurred
change in total mass of substances
From a complete and correctly written chemical equation, you can obtain the
chemical formulas of the reactants and products, relative amounts of the reactants and products, and physical states of the reactants and products
To balance a chemical equation, it is permissible to adjust the
coefficients
To balance a chemical equation, it may be necessary to adjust the
coefficients
The reaction 2C2H2(g) + 5O2(g) 4CO2(g) + 2H2O(l) is
combustion reaction
Tell what type of chemical reaction is represented by the following formula equation. Then balance the equation. C3H8(g) + O2(g) -> CO2(g) + H2O(l)
combustion, C3H8(g) + 5O2(g) -> 3CO2(g) + 4H2O(l)
Calcium carbonate, CaCO3, reacts to form calcium oxide, CaO, and carbon dioxide, CO2. What type of reaction is this?
decomposition
The reaction represented by the equation 2HgO(s) → 2Hg(l) + O2(g) is classified as a(n) ____________________ reaction
decomposition
2H2O(l) --> 2H2(g) + O2(g)
decomposition reaction
In what kind of reaction does a single compound produce two or more simpler substances?
decomposition reaction
The equation AX → A + X is the general equation for a
decomposition reaction
The reaction represented by the equation 2HgO(s) → 2Hg(l) + O2(g) is a(n)
decomposition reaction
The reaction represented by the equation 2KClO3(s) → 2KCl(s) + 3O2(g) is a(n)
decomposition reaction
The reaction represented by the equation Mg(s) + 2HCl(aq) → H2(g) + MgCl2(aq) is classified as a(n) ____________________ reaction
displacement
In what kind of reaction does one element replace a similar element in a compound?
displacement reaction
In a chemical equation, the symbol (aq) indicates that the substance is
dissolved in water
HCl(aq) + NaOH(aq) ---> NaCl(aq) + H2O(l)
double displacement reaction
In a reaction, the ions of two compounds exchange places in aqueous solution to form two new compounds. This reaction is called a
double-displacement reaction
In what kind of reaction do the ions of two compounds exchange places in aqueous solution to form two new compounds?
double-displacement reaction
The equation AX + BY → AY + BX is the general equation for a
double-displacement reaction
The reaction Pb(NO3)2(aq) + 2KI(aq) PbI2(s) + 2KNO3(aq) is a
double-displacement reaction
The reaction represented by the equation Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) is a
double-displacement reaction
Tell what type of chemical reaction is represented by the following formula equation. Then balance the equation. KBr(aq) + Mg(OH)2(aq) -> KOH(aq) + MgBr2(aq)
double-displacement, 2KBr(aq) + Mg(OH)2(aq) -> 2KOH(aq) + MgBr2(aq)
The decomposition of a substance by an electric current is called
electrolysis
Which of the following is a product that can be formed by double displacement reactions?
gas, precipitate, water
The replacement of bromine by chlorine in a salt is an example of a single-displacement reaction by
halogens
Active metals react with certain acids, such as hydrochloric acid, to yield a metal compound and
hydrogen
Group 1 metals react with water tterm-48o produce metal hydroxides and
hydrogen
When potassium reacts with water, one product formed is
hydrogen gas
The coefficients in a chemical equation
indicate the number of moles of each substance that react
Which of the following is a product in the reaction described by the word equation below? iron + copper(II) sulfate iron(II) sulfate + copper
iron(II) sulfate, copper
Oxides of active metals, such as CaO, react with water to produce
metal hydroxides
What does CH4 represent in the balanced chemical equation shown below? C + 2H2 -> CH4
one molecule of CH4
In one type of synthesis reaction, an element combines with oxygen to yield a(n)
oxide
A precipitate may form in a double-displacement reaction when
positive ions combine with negative ions
The production of a slightly soluble solid compound in a double-displacement reaction results in the formation of a
precipitate
When a slightly soluble solid compound is produced in a double-displacement reaction, a
precipitate is formed
An active metal and a halogen react to form a(n)
salt
A chemical equation is balanced when the
same number of each kind of atom appears in the reactants and in the products
What type of chemical reaction does the following chemical equation represent? 2HCl(aq) + Cr(s) H2(g)+ CrCl2(aq)
single-displacement
Cl2(g) + 2KBr(aq) 2KCl(aq) + Br2(l)
single-displacement reaction
The equation A + BX → AX + B is the general equation for a
single-displacement reaction
The reaction Mg(s) + 2HCl(aq) H2(g) + MgCl2(aq) is a
single-displacement reaction
The reaction represented by the equation Cl2(g) + 2KBr(aq) → 2KCl(aq) + Br2(l) is a(n)
single-displacement reaction
The reaction represented by the equation Mg(s) + 2HCl(aq) → H2(g) + MgCl2(aq) is a
single-displacement reaction
In the chemical reaction represented by the equation 2Cr(s) + 3O2(g) → 2CrO3(s), two chromium atoms combine with ____________________ oxygen atoms
six
In the reaction described by the word equation sodium + water sodium hydroxide + hydrogen gas
sodium hydroxide is a product, water is a reactant
In the chemical equation 2AlCl3(aq) + 3Pb(NO3)2 (aq) → 3PbCl2(s) + 2Al(NO3)3(aq), the state of PbCl2 is a(n)
solid
In which type of reaction do two or more compounds react to form one product?
synthesis
What type of chemical reaction is represented by the following word equation? iron + oxygen iron(II) oxide
synthesis
What type of chemical reaction results in the formation of a single product?
synthesis
In what kind of reaction do two or more substances combine to form a new compound?
synthesis reaction
The equation A + X → AX is the general equation for a(n)
synthesis reaction
The reaction represented by the equation 2Mg(s) + O2(g) → 2MgO(s) is a
synthesis reaction
Tell what type of chemical reaction is represented by the following formula equation. Then balance the equation. Ga(s) + S(s) -> Ga2S3(s)
synthesis, 2Ga(s) + 3S(s) -> Ga2S3(s)
In a chemical reaction
the mass of the reactants equals the mass of the products
When a binary compound decomposes, what is produced?
two elements
In a double-displacement reaction, hydrogen chloride and sodium hydroxide react to produce sodium chloride. Another product is
water
Magnesium hydroxide decomposes to yield magnesium oxide and
water
Many metal hydroxides decompose when heated to yield metal oxides and
water
