Reactions and Equations #1

Reactions and Equations #1
Balance these reactions by filling in the spaces for the coefficients. Also, tell what general type of reaction is
represented (composition, decomposition, replacement, double displacement, combustion)
1. ____H2(g) + ____Cl2(g) -----> ____HCl(g)
2. ____Mg(s) + ____O2(g) -----> ____MgO(s)
3. ____H2(g) + ____O2(g) -----> ____H2O(g)
4. ____Na(s) + ____O2(g) -----> ____Na2O(s)
5. ____Zn(s) + ____H2SO4(aq) -----> ____ZnSO4(aq) + ____H2(g)
6. ____Cl2(g) + ____AlBr3(aq) -----> ____Br2(l) + ____AlCl3(aq)
7. Aluminum metal reacts with hydrogen chloride gas to produce solid aluminum chloride and hydrogen gas.
8. Magnesium metal reacts with gaseous carbon dioxide when it is heated, yielding solid magnesium oxide and
solid carbon.
9. Why should you never change the subscripts in a formula in order to balance an equation?
10. Write the balanced equation that shows how ammonia gas is produced from the diatomic gases hydrogen and
nitrogen.

11. LiOH(aq) + H3PO4(aq) ----> H2O(l) + Li3PO4(aq)
12. NH4Cl(s) + Mg(OH)2(s) -----> NH3(g) + H2O(l) + MgCl2(s)
13. H2SO4(aq) + Ca(OH)2(s) -----> __________ + __________
14. (NH4) 3PO4(s) + NaOH(s) -----> ________ + ________ + ________
15. CaCO3(s) + HI(aq) -----> ________ + ________ + ________
16. HCN(aq) + Mg(s) -----> ________ + ________
17. Using any combination of the reagents listed here, write balanced equations showing how you could form the
compounds in a - e.
HCl Ca(OH)2 MgO Mg K2CO3 NH4Cl
a. MgCl2
b. H2
c. NH3
d. CaCl2
e. CO2
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Reactions and Equations #2
Write balanced equations for these. In the left margin, indicate rxn type.
1. HgO(s) � Hg(l) + O2(g)
2. Fe2O3(s) + C(s) � Fe(s) + CO(s)
3. Cl2(g) + NaBr(aq) � Br2(l) + NaCl(aq)
4. MgCO3(s) � MgO(s) + CO2(g)
5. BaCl2(aq) + NaOH(aq) �
6. NH4OH(aq) �
7. H2CO3(aq) �
8. C6H12O6 (S) + O2(g) �
9. Silverware needs to be cleaned occasionally after its sits around and becomes tarnished. It becomes tarnished
when sulfur, floating around in the air, reacts with the silver, becoming black silver sulfide. Sulfur molecules are S8.
10. When propane gas (chemical formula: C3H8) burns, carbon dioxide and water vapor are the products.
11. Model volcanoes are often made by kids in middle school for science fair projects that use baking soda and
vinegar as the "eruption". Baking soda is "sodium bicarbonate" or "sodium hydrogencarbonate" in chemicalese.
Vinegar's active ingredient is acetic acid. One of the products (there are three products) is sodium acetate:
NaC2H3O2. Think of the other two products and write the balanced equation.
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Some review, to keep your mind sharp and agile…
12. Consider acetaminophen, C8H9NO2, the active ingredient in Tylenol.
a. How many grams is 0.457 moles?
b. If a Tylenol tablet contains 500 mg of the active ingredient, shown above, how many moles is this?
c. How many moles of carbon atoms are there from #2?
d. What is the mass percent of carbon in Tylenol?
13. What is the difference between an emperical formula and a molecular formula?
14. What is the mass of 8.0 moles of carbon dioxide?
15. How many atoms of oxygen are in 4.5 moles of calcium hydroxide?
16. An unknown solution is left in the lab. It has either barium-, silver-, or sodium nitrate present. What could you
do to determine what solution has been left in the lab? Design a brief experiment. Write ppt rxns to show what you
are considering.
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Reactions and Equations #3
Here is some more practice. These are from the AP Chemistry test a few years ago.
For each reaction, give the completed, balanced equation as well as the reaction type.
(a) Solutions of zinc sulfate and sodium phosphate are mixed.
(b) Solutions of silver nitrate and lithium bromide are mixed.
(c) A stream of chlorine gas is passed through a solution of cold, dilute sodium bromide
solution.
(d) Excess hydrochloric acid solution is added to a solution of potassium sulfite.
(e) Solutions of sodium iodide and lead nitrate are mixed.
(f) A solution of ammonium hydroxide is added to a solution of iron (III) chloride.
(g) A solution of hydrogen peroxide is heated.
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(h) A piece of solid bismuth is heated
(i) A strip of copper metal is added to a concentrated solution of sulfuric acid.
(j) A strip of copper is immersed in dilute nitric acid.
(k) If 204.5 g of copper (II) nitrate is formed in the above reaction:
1. How many moles are formed?
2. How many atoms of oxygen are formed?
3. What is the mass percent of nitrogen in the copper (II) nitrate?
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Even more reactions & equations
1. Balance these reactions. Give reaction type for each, and complete each reaction, if it is not already completed.
a. LiOH(aq) + H3PO4(aq) ----> H2O(l) + Li3PO4(aq)
b. NH4Cl(s) + Mg(OH)2(s) ----> _________(g) + _________(l) + _________(aq)
c. CaO(s) + HNO3(aq) ---->
d. CuCO3(s) + HBr(aq) ---->
e. BaCl2(aq) + NaOH(aq) ----> Ba(OH)2(s) + NaCl(aq)
2. Write a balanced equation for the following descriptions of reactions.
a. When metals react with acids, hydrogen gas and a salt are produced. The salt is formed from the metal cation
and the acid anion. If the salt that is produced is soluble in water, it will be dissolved in the water that is
produced. Write the equation that takes place between calcium metal and phosphoric acid solution.
b. When metal carbonates are heated, carbon dioxide gas is produced along with the solid oxide of the metal.
Write a balanced equation for the formation of barium oxide from barium carbonate. (Barium ions have a
charge of +2.)
c. Hydrogen peroxide (a liquid at room temperature) decomposes when exposed to sunlight. (That's why it
always comes in brown opaque bottles.) Water is one product, and the other product is a gas that is able to
relight a glowing splint. Write the equation showing the decomposition of hydrogen peroxide.
3. Predict the products and balance the reactions. Give reaction type. REFER TO YOR NOTES!
a. BaSO4(aq) + Ag(s) ----> ___________(s) + __________(aq)
b. Mg(s) + HCl(aq) ----> __________(aq) + __________(g)
c. Ca(NO3)2(aq) + Mg(s) ----> __________(aq) + __________(s)
d. MgCO3(s) ----->
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e. H2(g) + O2(g) ---->
f. Zn(s) + AgNO3(aq) ---->
g. C5H10(s) + O2(g) ---->
h. LiOH(aq) + H2SO4(aq) ---->
i. NH4Br(s) + NaOH(aq) ---->
j. MgCO3(s) + H2SO4(aq) ---->
4. Write the two half-cell reactions that take place when zinc metal is placed into a solution of silver nitrate, and
label them appropriately as "reduction" or "oxidation".
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Equations and Reactions Review
1. Balance these reactions.
a. MgCO3(s) ----> MgO(s) + CO2(g)
b. Fe2O3(s) + C(s) ----> Fe(s) + CO(g)
c. BaCl2(aq) + NaOH(aq) ----> Ba(OH)2(s) + NaCl(aq)
2. Predict the products and balance the reactions. In the margin, give reaction type.
a. ZnSO4(aq) + Mg(s) ----> ___________(s) + __________(aq)
b. MgO(s) + HCl(aq) ----> __________(aq) + __________(l)
c. Ca(s) + HNO3(aq) ----> __________(aq) + __________(g)
d. Na2CO3(s) ----->
e. C(s) + O2(g) ---->
f. Zn(s) + AgNO3(aq) ---->
g. K(s) + O2(g) ---->
h. NaOH(aq) + H3PO4(aq) ---->
i. NH4Cl(s) + KOH(aq) ---->
j. (NH4)2CO3(s) + H2SO4(aq) ---->
3. Write a balanced equation for the following descriptions of reactions.
a. Sodium metal burns with a bright yellow flame, producing solid sodium oxide.
b. When potassium chlorate is heated in a test tube, it gives off a gas that is capable of relighting a glowing
splint, and a white crystalline salt is left behind in the test tube.
c. Nitrogen gas and hydrogen gas react at high pressure and temperature, producing ammonia gas. This is
called the "Haber process".
d. “Hexane” is a common non-polar solvent used in organic chemistry labs. When it burns, carbon dioxide
and water vapor are the only products.
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4. Balance and type the following reaction, and then draw a fully labeled energy level diagram. Include bond
making and bond breaking, activation energy, total energy, starting and ending materials. Endo- or exothermic?
C2H5OH + O2 � CO2 + H2O
5. Here is a partial list of elements in order of decreasing "activity". Determine if a reaction will occur. If so,
write the completed, balanced equation.
Metals: Li K Ca Na Mg Al Zn Cr Fe Ni Sn Pb H Cu Ag Hg Pt Au
Non-metals: F Cl Br I
a. Mg + AlCl3 �
b. FeSO4 + Ni �
c. NaI + Cl2 �
d. HCl + Al �
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Practice Test: Reactions and Equations
You may use a calculator, your “ion sheet”, and a periodic table during this test.
1. Complete the following reactions (if they react) and balance them.
a. H2SO3(aq) + Al(OH)3(s) � ________(l) + ________(aq)
b. NiCO3(s) __________(s) + __________(g)
c. HBr (aq) + Mg (s) � _________(aq) + _______(g)
d. C8H18(l) + O2(g) �
e. CuCO3(s) + HClO3(aq) �
f. ___________ (s) + ______________(s) � NH3(g) + H2O (l) + Na2SO4 (aq)
3. Write the total reaction, and the oxidation and reduction half reactions that occur when Mg is burned in pure
oxygen. ID what is oxidized, what is reduced.
Total rxn:
Oxidation rxn:
Reduction rxn:
Questions from the Labs and Demonstrations
4. Dinitrogen oxide, or nitrous oxide (laughing gas) can be prepared by the thermal decomposition of
ammonium nitrate. The other product is water. Write the balanced equation for this.
One of the reactions you saw involved placing a piece of copper into an aqueous solution of silver nitrate. What
would happen if a piece of silver were placed into an aqueous solution of copper nitrate?
One of the reactions that you saw was the decomposition of hydrogen peroxide. In that reaction a gas is formed
which relights a glowing splint. Write the balanced equation for the reaction.
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When limewater (a solution of calcium hydroxide) has a certain gas bubbled through it, a precipitate forms.
Write the balanced equation that shows why limewater turns cloudy.
5. Suppose that you are given a cube of magnesium metal of edge length 1.0 cm. Calculate the number of Mg
atoms in the cube. Atoms are spherical in shape, therefore the Mg atoms in the cube cannot fill all the available
space. If only 74% of the space inside the cube is taken up by Mg atoms, calculate the radius in picnometers of
a Mg atom. The density of Mg is 1.74 g/cm 3 , and the volume of a sphere is
with a "known" value.
4 ⋅ r
3
3
⋅π . Compare your value
5. Draw a fully-labeled "energy level diagram" that shows the energy changes that take place when gasoline,
C8H18, is burned in air. Include the balanced equation on your diagram. Label all parts properly.
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Many Chemical Reactions Demonstrations
You will view numerous demonstrations during this unit. For each, you will briefly summarize what for each reaction, as
well as write balanced equations and determine the reaction type. All the information will be recorded on this sheet.
For each demonstrated reaction, hypothesize a formula and reaction type, describe the reaction, and write a completed,
balanced equation for each. Label each reaction with the proper reaction type.
# Reactants Hypothesis – may be equations, or
description
Actual description upon viewing
1 Calcium and water
Balanced eqn and rxn type
2 Heating baking soda
Balanced eqn and rxn type
3 Sodium in water
Balanced eqn and rxn type
4 magnesium in
hydrochloric acid
Balanced eqn and rxn type
5 magnesium in nitric
acid
Balanced eqn and rxn type
6 chalk in sulfuric acid
Balanced eqn and rxn type
7 copper wire in silver
nitrate solution
Balanced eqn and rxn type
8 combustion of
methanol
Balanced eqn and rxn type
9 decomposition of
hydrogen peroxide
Balanced eqn and rxn type
10 iron (steel wool) heated
in pure oxygen
Balanced eqn and rxn type
11 ammonia and
hydrogen chloride
Balanced eqn and rxn type
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12 sulfuric acid and
sucrose (table sugar)
Balanced eqn and rxn type
13 rapid oxidation of
sucrose
Balanced eqn and rxn type
14 decomposition of
ammonium dichromate
Balanced eqn and rxn type
15 heating copper
carbonate
Balanced eqn and rxn type
16 heating potassium
chlorate
Balanced eqn and rxn type
17 burning propane gas
Balanced eqn and rxn type
18 electric current passing
through water
Balanced eqn and rxn type
19 aluminum and
iron(III) oxide
Balanced eqn and rxn type
20 heating copper(II)
sulfate pentahydrate
Balanced eqn and rxn type
21 water and anhydrous
copper(II) sulfate
Balanced eqn and rxn type
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23
24
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