Term
| Why do chemists have to balance chemical equations? |
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Definition
| To satisfy the requirement that the number of atoms of each element are the same on the reactant and product sides of the equation. |
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Term
Identify the coefficients and subscripts in this balanced equation:
3 CuCl2 + 2 Al → 2 AlCl3 + 3 Cu |
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Definition
3 CuCl2 + 2 Al → 2 AlCl3 + 3 Cu
The underlined numbers are the coefficient.
The numbers in red are the subscripts. |
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Term
Complete an atom inventory for the following reaction:
3 Na2SO4 + 2 AlCl3 → 6 NaCl + Al2(SO4)3 |
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Definition
Na = 6
S = 3
O = 12
Al = 2
Cl = 6 |
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Term
Explain why this equation is written incorrectly:
Water can be broken down into its elements,
H2O → H2 + O |
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Definition
Oxygen is a diatomic element. Should be
2 H2O → 2 H2 + O2 |
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Term
Calculate the molar mass of calcium hydroxide. |
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Definition
| Ca(OH)2 has a molar mass of 74 g/mol. |
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Term
Calculate the molar mass of barium chloride dihydrate.
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Definition
BaCl2 . 2 H2O
molar mass = 243 g/mol |
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Term
Calculate the percent composition of each element in the compound KNO3.
Also, name this compound.
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Definition
K = 39 %
N = 14 %
O = 48 %
The name is potassium nitrate. |
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Term
0.75 moles of CaCl2 would have how many formula units of calcium chloride?
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Definition
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Term
| 2.5 grams of AuCl2 would have how many moles? |
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Definition
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Term
Write and balance the following equation:
potassium reacts with aluminum chloride, forming aluminum metal and potassium chloride. |
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Definition
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Term
Balance this equation:
C9H18 + O2 → CO2 + H2O |
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Definition
2 C9H18 +27 O2 → 18 CO2 + 18 H2O |
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Term
What are the seven diatomic elements?
Write their symbols. |
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Definition
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Term
Convert 1.9 x 1021 molecules of water to grams.
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Definition
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Term
Calculate the mass of zinc in 9.7 grams of Zn(NO3)2. |
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Definition
| First find % Zn in Zn(NO3)2. It is 34%. Now, multiply 34% by 9.7 grams, to get 3.3 grams Zn. |
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Term
Convert 5.2 moles of Cu to grams.
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Definition
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Term
Convert 34.2 grams of oxygen gas to molecules.
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Definition
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Term
| The number 6.02 x 1023, or one mole, is named after this scientist. |
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Definition
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Term
Write and balance this equation:
strontium metal reacts with water to produce strontium hydroxide and hydrogen gas. |
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Definition
| 1 Sr + 2 H2O → 1 Sr(OH)2 + 1 H2 |
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Term
Write and balance this equation:
silver nitrate and calcium chloride combine to produce silver chloride and calcium nitrate. |
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Definition
| 2 AgNO3 + 1 CaCl2→ 2 AgCl + 1 Ca(NO3)2 |
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Term
| Explain the connection between the terms elements, ores, and minerals. |
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Definition
| Ores are large rock formations that contain various minerals. Minerals are ionic compounds that contain metal elements like copper, iron, zinc, etc. These ores are mined from the earth to extract the metal elements from the mineral compounds. |
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Term
| Sand is primarily ccomposed of the mineral quartz. Quartz is silicon dioxide, SiO2. Calculate the molar mass of SiO2 and calculate the % of oxygen. |
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Definition
molar mass of SiO2 = 28 + 16(2) = 60 g/mol.
The % oxygen = 32/60 = 53% |
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Term
| When converting from grams to moles, you (multiply / divide) by the molar mass of the substance. |
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Definition
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Term
| A mole of particles is how many particles? |
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Definition
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Term
| The word particle is a generic term. When do we call compounds molcules and when do we call compounds formula units? |
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Definition
| Compounds made up of only nonmetals are called molecules. Compounds that are ionic (contain a metal) are called formula units. |
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