1.
The disinfectant hydrogen peroxide, H_{2}O_{2}, decomposes to form water and oxygen gas. How many moles of O_{2} will result from the decomposition of 5 mol of hydrogen peroxide?
Correct Answer
C. 3 mol H2O2
Explanation
Given: 5 mol H2O2
Unknown: ? mol O2
5 mol H2O2 x (1 mol O2/2 mol H2O2) = 2.5 mol = 3 mol O2
*Although 2.5 mol O2 is technically correct, your answer must include the correct number of significant figures (which in this instance is 1). The answer is rounded to 3.
2.
Starting with 31g of Al in the following reaction will produce hao many grams of Na?
Na3PO4 + Al ---> AlPO4 + 3Na
Correct Answer
C. 79g
Explanation
In the given reaction, the stoichiometric ratio between Al and Na is 1:3. This means that for every 1 gram of Al reacted, 3 grams of Na will be produced. Since we are starting with 31g of Al, we can calculate the amount of Na produced by multiplying 31g by the ratio of Na to Al (3/1). This gives us 93g of Na. However, we need to consider the molar masses of the elements involved. The molar mass of Al is 26.98 g/mol and the molar mass of Na is 22.99 g/mol. By calculating the molar masses of Al and Na in the given reaction, we find that 1 mole of Al reacts to produce 3 moles of Na. This means that 26.98g of Al reacts to produce 3(22.99g) = 68.97g of Na. Therefore, starting with 31g of Al will produce approximately 68.97g of Na, which is closest to the given answer of 79g.
3.
If you counted 6.0 x 10^24 molecules of hydrogen gas how many molecules of oxygen gas will be need to completely react the amount according to the following equation?
2H2 + O2 ---> 2H2O
Correct Answer
C. 3.0 x 10^24
Explanation
The balanced equation shows that 2 molecules of hydrogen gas react with 1 molecule of oxygen gas to produce 2 molecules of water. Therefore, if 6.0 x 10^24 molecules of hydrogen gas are present, half that amount of oxygen gas, which is 3.0 x 10^24 molecules, will be needed to completely react with the hydrogen gas.
4.
40.0g of Sugar(C6H12O6) will product what volume of carbon dioxide according to the following equation?
C6H12O6 + 6O2 ---> 6H2O + 6CO2
Correct Answer
D. 29.9L
Explanation
When 1 mole of sugar (C6H12O6) reacts, it produces 6 moles of carbon dioxide (6CO2). To find the volume of carbon dioxide produced from 40.0g of sugar, we need to convert the mass of sugar to moles using its molar mass. The molar mass of sugar is 180.16 g/mol. Therefore, 40.0g of sugar is equal to 40.0g / 180.16 g/mol = 0.222 mol. Since the molar ratio between sugar and carbon dioxide is 1:6, the number of moles of carbon dioxide produced is 0.222 mol x 6 = 1.332 mol. Finally, we can use the ideal gas law to convert moles to volume using the molar volume of a gas at standard temperature and pressure (STP), which is 22.4 L/mol. Therefore, the volume of carbon dioxide produced is 1.332 mol x 22.4 L/mol = 29.9L.
5.
When reacting 448L of hydrogen gas with oxygen gas how many grams of water can be produced?
2H2 + O2 ---> 2H2O
Correct Answer
C. 362L
Explanation
The given balanced chemical equation shows that 2 moles of hydrogen gas react with 1 mole of oxygen gas to produce 2 moles of water. Since the volume of a gas is directly proportional to the number of moles, we can conclude that 2 moles of hydrogen gas will react with 1 mole of oxygen gas to produce 2 moles of water, regardless of the volume. Therefore, the volume of the gases (448L, 360L, 361L, 362L, 367L) is irrelevant to the amount of water produced.
6.
Starting with 20.5L of hydrogen gas how many molecules of amonia can be made according to this equation?
N2 + 3H2 ---> 2NH3
Correct Answer
B. 3.67 x 10^23
Explanation
According to the balanced chemical equation, 1 molecule of N2 reacts with 3 molecules of H2 to produce 2 molecules of NH3. Therefore, the number of moles of H2 can be calculated by dividing the given volume (20.5L) by its molar volume at STP. Then, using the mole ratio from the balanced equation, the number of moles of NH3 can be determined. Finally, the number of molecules of NH3 can be obtained by multiplying the number of moles by Avogadro's number (6.022 x 10^23). The correct answer of 3.67 x 10^23 represents the number of molecules of NH3 that can be made.
7.
3.50 x 10^25 compounds of calcium carbonate will produce what volume of carrbon dioxide according to the following equation?
CaCO3 ---> CaO + CO2
Correct Answer
C. 1300L
Explanation
According to the equation, one mole of calcium carbonate produces one mole of carbon dioxide. Since the question states that there are 3.50 x 10^25 compounds of calcium carbonate, we can assume that there are 3.50 x 10^25 moles of calcium carbonate. Therefore, there will be an equal number of moles of carbon dioxide produced. Using the ideal gas law, we can calculate the volume of carbon dioxide at standard temperature and pressure (STP), which is 22.4 L/mol. Multiplying 3.50 x 10^25 moles by 22.4 L/mol gives us a volume of approximately 7.84 x 10^26 L. However, this value is not one of the options provided. Therefore, the correct answer must be the closest option, which is 1300L.
8.
If 25.0 g of each reactant were used in performing the following reaction, which would be the limiting reactant?
3PbO_{2} + Cr_{2}(SO_{4})_{3} + K_{2}SO_{4} + H_{2}O Â® 3PbSO_{4} + K_{2}Cr_{2}O_{7} + H_{2}SO_{4}
Correct Answer
A. PbO2
Explanation
PbO2 is the limiting reactant because it is the reactant that will be completely consumed first, limiting the amount of product that can be formed.
9.
Na + Cl_{2} --> NaCl (unbalanced)How many moles of chlorine gas (Cl_{2}) would react with 5.0 moles of sodium (Na)
according to the following chemical equation?
Correct Answer
D. 2.5
Explanation
In the given chemical equation, the balanced equation is 2Na + Cl2 -> 2NaCl. This means that 1 mole of Cl2 reacts with 2 moles of Na to produce 2 moles of NaCl. Therefore, to react with 5.0 moles of Na, we would need 2.5 moles of Cl2, which is the correct answer.
10.
Na + Cl_{2} --> NaCl (unbalanced)Using the equation (after it is balanced) above, determine the amount of
product that
can be produced from 24.7 g Na. (in grams)
Correct Answer
B. 62
Explanation
The balanced equation shows that 2 moles of Na react with 1 mole of Cl2 to produce 2 moles of NaCl. To determine the amount of product that can be produced from 24.7 g of Na, we need to convert the mass of Na to moles. The molar mass of Na is 22.99 g/mol, so 24.7 g of Na is approximately 1.07 moles. Since the ratio of Na to NaCl is 2:2, the same number of moles of NaCl will be produced. Therefore, the amount of product that can be produced from 24.7 g of Na is approximately 1.07 moles or 62 grams.
11.
In the reaction C_{8}H_{18} + O_{2} --> CO_{2}
+ H_{2}O (unbalanced)If 27.3g of C_{8}H_{18} are combusted, what mass of water
will be produced?( in grams)
Correct Answer
E. 37.8
Explanation
When C8H18 is combusted, it reacts with O2 to produce CO2 and H2O. The balanced equation for the reaction is C8H18 + 12.5O2 -> 8CO2 + 9H2O. From the balanced equation, we can see that for every 1 mole of C8H18 combusted, 9 moles of H2O are produced. To find the mass of water produced, we need to convert the given mass of C8H18 to moles using its molar mass, and then use the mole ratio from the balanced equation to calculate the moles of water produced. Finally, we convert the moles of water to grams using the molar mass of water. The correct answer is 37.8 grams.
12.
CH_{4}
+ O_{2} -->
CO_{2}
+
2 H_{2}OHow
many moles of O_{2}
are required to burn 0.5 moles of CH_{4}?
Correct Answer
A. 1
Explanation
To balance the chemical equation, we need one mole of O2 for every mole of CH4. Therefore, if we have 0.5 moles of CH4, we will need 0.5 moles of O2 to completely burn it. Hence, the correct answer is 1.
13.
NaOH
+
HCl --> NaCl
+
H_{2}OHow
many grams of NaOH will react with 36.5 g of HCl? ( in grams)
Correct Answer
A. 40
Explanation
In the balanced chemical equation, the stoichiometric ratio between NaOH and HCl is 1:1. This means that for every 1 mole of NaOH, 1 mole of HCl will react. The molar mass of HCl is 36.5 g/mol. Since the stoichiometric ratio is 1:1, the mass of NaOH that will react with 36.5 g of HCl will also be 36.5 g. Therefore, the correct answer is 40 g.
14.
How many moles of water is formed from the combustion of 5 moles of hydrogen gas in oxygen gas?
Correct Answer
C. 5
Explanation
When hydrogen gas (H2) combusts with oxygen gas (O2), water (H2O) is formed. The balanced chemical equation for this reaction is 2H2 + O2 -> 2H2O. This equation shows that for every 2 moles of hydrogen gas, 2 moles of water are formed. Therefore, if 5 moles of hydrogen gas are combusted, it will produce 5 moles of water.
15.
Methane gas (CH_{4}) gets burned in oxygen (O_{2}) to form carbon dioxide (CO_{2}) and water vapor (H_{2}O). The balanced reaction is
Correct Answer
C. CH4 + 2O2 --> CO2 + 2H2O
Explanation
The balanced reaction for the combustion of methane gas in oxygen is CH4 + 2O2 --> CO2 + 2H2O. This equation shows that one molecule of methane reacts with two molecules of oxygen to produce one molecule of carbon dioxide and two molecules of water vapor. This equation follows the law of conservation of mass, as the number of atoms of each element is equal on both sides of the equation.
16.
Methane gas (CH_{4}) gets burned in oxygen (O_{2}) to form carbon dioxide (CO_{2}) and water vapor (H_{2}O). If I burn 10 grams of methane, how many grams of CO_{2} will be produced?
Correct Answer
D. 27.4 grams of CO2
Explanation
When methane gas (CH4) is burned in oxygen (O2), it reacts to form carbon dioxide (CO2) and water vapor (H2O). The balanced chemical equation for this reaction is: CH4 + 2O2 -> CO2 + 2H2O. From the equation, we can see that for every 1 mole of methane burned, 1 mole of carbon dioxide is produced. The molar mass of methane is 16 g/mol, so 10 grams of methane is equal to 10/16 = 0.625 moles. Therefore, 0.625 moles of carbon dioxide will be produced, which is equal to 0.625 x 44 = 27.5 grams. Therefore, the correct answer is 27.4 grams of CO2.
17.
In the decomposition of water to hydrogen gas and oxygen gas, how many moles of water is needed to produce 10.0 moles of oxygen gas?
Correct Answer
D. 20.0
Explanation
To determine the number of moles of water needed to produce 10.0 moles of oxygen gas, we need to use the balanced chemical equation for the decomposition of water: 2H2O -> 2H2 + O2. From the equation, we can see that for every 2 moles of water, we obtain 1 mole of oxygen gas. Therefore, to produce 10.0 moles of oxygen gas, we need twice that amount of water, which is 20.0 moles.
18.
In the decomposition of water to hydrogen gas and oxygen gas, how many
moles of water is needed to produce 32 grams of oxygen gas?
Correct Answer
D. 2.0
Explanation
To determine the number of moles of water needed to produce 32 grams of oxygen gas, we need to use the molar mass of oxygen gas. The molar mass of oxygen gas (O2) is 32 g/mol. Since the molar ratio between water and oxygen gas in the decomposition reaction is 2:1, we can conclude that 2 moles of water are needed to produce 32 grams of oxygen gas. Therefore, the correct answer is 2.0.
19.
Coal can be converted to methane gas by a process called coal gasification. The equation for the reaction is the following:2 C (s) + 2 H_{2}O (l) --> CH_{4} (g) + CO_{2} (g)What mass in grams of carbon is required to react with water to form 1.00 mol CH_{4}?
Correct Answer
B. 24.0 g C
Explanation
Given: 1.00 mol CH4
Unknown: ? g C
1.00 mol CH4 x (2 mol C/1 mol CH4) x (12.01 g/mol C) = 24.02 = 24.0 g C
*Although 24.02 g C is technically correct, your answer must include the correct number of significant figures (which in this instance is 3). The answer is rounded to 24.0.
20.
Nitrogen combines with oxygen in the atmosphere during lightning flashes to form nitrogen monoxide, NO, which then reacts further with O2 to produce nitrogen dioxide, NO2, according to the following equation:N_{2} (g) + O_{2} (g) --> 2 NO (g)2 NO (g) + O_{2} (g) --> 2 NO_{2} (g) * Hint: Use this equation to answer the question.What mass of NO_{2} is formed when NO reacts with 386 g of O_{2}?
Correct Answer
A. 1110 g NO2
Explanation
Given: 386 g O2
Unknown: ? g NO2
386 g O2 x (1/32.00g/mol O2) x (2 mol NO2/1 mol O2) x (46.01 g/mol NO2) = 1109.99125 = 1110 g NO2
*Although 1109.99125 g NO2 is technically correct, your answer must include the correct number of significant figures (which in this instance is 3). The answer must be rounded to 1110.
21.
Iron is produced from iron ore through the following reaction in a blast furnace:Fe_{2}O_{3} (s) + 3 CO (g) --> 2 Fe (s) + 3 CO_{2} (g)If 4.00 g of Fe_{2}O_{3} are available to react, how many moles of CO are needed?(round answer to 3 sigfigs)
Correct Answer
D. 0.0751 mol CO
Explanation
Given: 4.00 g Fe2O3
Unknown: ? mol CO
4.00 g Fe2O3 x (1/159.70 g/mol Fe2O3) x (3 mol CO/1 mol Fe2O3) = 0.075141 = 0.0751 mol CO
*Although 0.075141 mol CO is technically correct, your answer must include the correct number of significant figures (which in this instance is 3). You must round your answer to 0.0751.
22.
If you have 4.5 moles of lead(IV) nitrate how many moles of silver nitrate can be produced according to the following reaction?Pb(NO3)4 + 4AgCl ---> 4AgNO3 + PbCl4
Correct Answer
D. 18 moles
Explanation
In the given reaction, 1 mole of Pb(NO3)4 reacts with 4 moles of AgCl to produce 4 moles of AgNO3 and 1 mole of PbCl4. Therefore, if we have 4.5 moles of Pb(NO3)4, we can say that we will be able to produce 4.5 times the moles of AgNO3. So, 4.5 moles of Pb(NO3)4 will produce 4.5 x 4 = 18 moles of AgNO3.
23.
Using the following equation how many liters of hydrogen gas will be needed to react with 5.0L of oxygen gas?2H2 + O2 ---> 2H2O
Correct Answer
C. 10 L
Explanation
In the balanced chemical equation, the stoichiometric ratio between hydrogen gas and oxygen gas is 2:1. This means that for every 2 moles of hydrogen gas, 1 mole of oxygen gas is required for the reaction to occur. Since the question states that there are 5.0L of oxygen gas, we can conclude that we need twice that amount of hydrogen gas, which is 10 L. Therefore, the correct answer is 10 L.
24.
If 25g of NaCl is produced by the following reaction howmany atome of sodium would be required?2Na + Cl2 ---> 2NaCl
Correct Answer
B. 2.6 x 10^23
Explanation
In the given reaction, 2 moles of sodium (2Na) react with 1 mole of chlorine (Cl2) to produce 2 moles of sodium chloride (2NaCl). The molar mass of sodium chloride (NaCl) is 58.44 g/mol.
To find the number of atoms of sodium required to produce 25g of sodium chloride, we need to convert the given mass to moles using the molar mass.
25g NaCl * (1 mol NaCl / 58.44 g NaCl) = 0.428 mol NaCl
Since the reaction produces 2 moles of NaCl for every 2 moles of sodium, the number of moles of sodium required is also 0.428 mol.
Finally, we can convert the moles of sodium to atoms using Avogadro's number (6.022 x 10^23 atoms/mol).
0.428 mol Na * (6.022 x 10^23 atoms/mol) = 2.58 x 10^23 atoms
Therefore, the correct answer is 2.6 x 10^23 atoms.
25.
If starting with 1.2 x 10^24 atoms of potassium how many grams of potassium oxide can you produce using the following equation? (round to 2 sig figs)4K + O2 ---> 2K2O
Correct Answer
D. 94g
Explanation
When balancing the equation 4K + O2 ---> 2K2O, we can see that 4 moles of potassium (K) react with 1 mole of oxygen (O2) to produce 2 moles of potassium oxide (K2O). To find the mass of potassium oxide produced, we need to convert the number of atoms of potassium to moles using Avogadro's number. 1.2 x 10^24 atoms of potassium is equal to 1.2 x 10^24 / 6.022 x 10^23 = 1.99 moles of potassium. From the balanced equation, we can see that 4 moles of potassium reacts to produce 2 moles of potassium oxide. Therefore, 1.99 moles of potassium will produce (2/4) x 1.99 = 0.995 moles of potassium oxide. Finally, we can calculate the mass of potassium oxide using its molar mass of 94 g/mol: 0.995 moles x 94 g/mol = 93.43 g. Rounded to 2 significant figures, the answer is 94g.