Q. How many grams of KCl are needed to prepare 0.5 moles of KCl solution?
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A.
37.5 g
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B.
74.5 g
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C.
50 g
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D.
100 g
Solution
The molar mass of KCl is 39 g/mol (K) + 35.5 g/mol (Cl) = 74.5 g/mol. Therefore, 0.5 moles of KCl will weigh 0.5 x 74.5 g = 37.25 g.
Correct Answer: B — 74.5 g
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Q. How many grams of KCl are needed to prepare 0.5 moles of KCl solution? (Molar mass of KCl = 74.5 g/mol)
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A.
37.25 g
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B.
74.5 g
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C.
148.5 g
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D.
18.5 g
Solution
To find the mass, use the formula: mass = moles x molar mass. Thus, 0.5 moles x 74.5 g/mol = 37.25 g.
Correct Answer: A — 37.25 g
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Q. How many grams of KCl are needed to prepare 0.5 moles of KCl?
-
A.
37.5 g
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B.
45 g
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C.
50 g
-
D.
60 g
Solution
The molar mass of KCl is approximately 74.5 g/mol. Therefore, 0.5 moles of KCl will weigh 0.5 x 74.5 g = 37.25 g.
Correct Answer: B — 45 g
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Q. How many grams of KCl can be produced from the reaction of 10 g of K with excess Cl2?
-
A.
74.5 g
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B.
37.25 g
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C.
148.5 g
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D.
18.5 g
Solution
10 g of K = 0.25 moles. K + Cl2 → KCl, so 0.25 moles of KCl = 0.25 * 74.5 g = 18.625 g.
Correct Answer: A — 74.5 g
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Q. How many grams of NaOH are needed to neutralize 1 mole of HCl?
-
A.
40 g
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B.
36.5 g
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C.
58.5 g
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D.
23 g
Solution
The reaction between NaOH and HCl is 1:1. The molar mass of NaOH is 40 g/mol, so 1 mole of NaOH is needed, which weighs 40 g.
Correct Answer: C — 58.5 g
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Q. How many grams of NaOH are needed to prepare 0.5 moles of NaOH solution?
-
A.
20 g
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B.
40 g
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C.
10 g
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D.
30 g
Solution
The molar mass of NaOH is 40 g/mol. Therefore, to prepare 0.5 moles, you need 0.5 x 40 g = 20 g.
Correct Answer: B — 40 g
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Q. How many grams of NaOH are needed to prepare 0.5 moles of NaOH solution? (Molar mass of NaOH = 40 g/mol)
-
A.
20 g
-
B.
40 g
-
C.
10 g
-
D.
30 g
Solution
To find the mass, use the formula: mass = moles × molar mass. Thus, 0.5 moles × 40 g/mol = 20 g.
Correct Answer: A — 20 g
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Q. How many grams of solute are needed to prepare 0.5 L of a 1 M NaCl solution? (Molar mass of NaCl = 58.5 g/mol)
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A.
29.25 g
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B.
58.5 g
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C.
14.625 g
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D.
0.5 g
Solution
Mass of solute = moles × molar mass = 1 mol × 58.5 g/mol = 58.5 g. For 0.5 L, it is 0.5 mol × 58.5 g/mol = 29.25 g.
Correct Answer: A — 29.25 g
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Q. How many grams of solute are needed to prepare 2 L of a 1 M solution? (Molar mass = 58.5 g/mol)
-
A.
58.5 g
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B.
117 g
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C.
29.25 g
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D.
145 g
Solution
Grams of solute = moles x molar mass = 2 moles x 58.5 g/mol = 117 g.
Correct Answer: B — 117 g
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Q. How many molecules are present in 2 moles of water (H2O)?
-
A.
6.022 x 10^23
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B.
1.2044 x 10^24
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C.
3.011 x 10^23
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D.
12.044 x 10^24
Solution
Number of molecules = moles x Avogadro's number = 2 moles x 6.022 x 10^23 molecules/mole = 1.2044 x 10^24 molecules.
Correct Answer: B — 1.2044 x 10^24
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Q. How many moles are in 1.5 kg of KCl?
Solution
Molar mass of KCl = 39 + 35.5 = 74.5 g/mol. Number of moles = mass/molar mass = 1500 g / 74.5 g/mol ≈ 20.1 moles.
Correct Answer: B — 20
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Q. How many moles are in 10 grams of NaOH?
-
A.
0.25
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B.
0.5
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C.
0.75
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D.
1
Solution
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol. Number of moles = mass/molar mass = 10 g / 40 g/mol = 0.25 moles.
Correct Answer: A — 0.25
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Q. How many moles are in 100 grams of CaCO3?
Solution
Molar mass of CaCO3 = 40 + 12 + 3*16 = 100 g/mol. Number of moles = mass/molar mass = 100 g / 100 g/mol = 1 mole.
Correct Answer: A — 1
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Q. How many moles are in 180 grams of water?
Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = 180 g / 18 g/mol = 10 moles.
Correct Answer: A — 1
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Q. How many moles are in 200 grams of H2O?
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A.
11.11
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B.
10
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C.
9
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D.
8.89
Solution
Molar mass of H2O = 18 g/mol. Number of moles = mass / molar mass = 200 g / 18 g/mol = 11.11 moles.
Correct Answer: A — 11.11
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Q. How many moles are in 200 grams of H2SO4?
Solution
Molar mass of H2SO4 = 2 + 32 + 16*4 = 98 g/mol. Number of moles = 200 g / 98 g/mol = 2.04 moles.
Correct Answer: B — 2
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Q. How many moles are in 36 grams of water (H2O)?
Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = mass/molar mass = 36 g / 18 g/mol = 2 moles.
Correct Answer: A — 1
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Q. How many moles are in 5.6 liters of a gas at STP?
Solution
At STP, 1 mole of gas occupies 22.4 L. Number of moles = volume / molar volume = 5.6 L / 22.4 L/mole = 0.25 moles.
Correct Answer: C — 1
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Q. How many moles are in 5.6 liters of an ideal gas at STP?
Solution
At STP, 1 mole of gas occupies 22.4 L. Therefore, number of moles = 5.6 L / 22.4 L/mole = 0.25 moles.
Correct Answer: B — 0.5
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Q. How many moles are in 50 grams of CaCO3?
Solution
Molar mass of CaCO3 = 100 g/mol. Number of moles = mass / molar mass = 50 g / 100 g/mol = 0.5 moles.
Correct Answer: B — 1
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Q. How many moles are in 50 grams of H2O?
-
A.
2.78
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B.
1.39
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C.
0.56
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D.
3.06
Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = mass/molar mass = 50 g / 18 g/mol = 2.78 moles.
Correct Answer: B — 1.39
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Q. How many moles are in 50 grams of NaOH?
Solution
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol. Number of moles = mass/molar mass = 50 g / 40 g/mol = 1.25 moles.
Correct Answer: B — 0.5
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Q. How many moles are in 50 grams of sodium (Na)?
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A.
1.08
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B.
2.5
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C.
0.5
-
D.
0.25
Solution
Molar mass of Na = 23 g/mol. Number of moles = mass / molar mass = 50 g / 23 g/mol ≈ 2.17 moles.
Correct Answer: A — 1.08
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Q. How many moles are in 500 mL of a 2 M NaCl solution?
Solution
Moles = molarity x volume (in L) = 2 M x 0.5 L = 1 mole.
Correct Answer: B — 1
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Q. How many moles are in 88 grams of CH4?
Solution
Molar mass of CH4 = 12 + 4*1 = 16 g/mol. Number of moles = mass/molar mass = 88 g / 16 g/mol = 5.5 moles.
Correct Answer: B — 2
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Q. How many moles are in 88 grams of O2?
Solution
Molar mass of O2 = 16*2 = 32 g/mol. Number of moles = mass/molar mass = 88 g / 32 g/mol = 2.75 moles.
Correct Answer: B — 2
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Q. How many moles are in 88 grams of oxygen (O2)?
Solution
Molar mass of O2 = 32 g/mol. Number of moles = mass / molar mass = 88 g / 32 g/mol = 2.75 moles.
Correct Answer: A — 2
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Q. How many moles of CO2 are produced from the complete combustion of 1 mole of C3H8?
Solution
C3H8 + 5O2 → 3CO2 + 4H2O. 1 mole of C3H8 produces 3 moles of CO2.
Correct Answer: A — 3
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Q. How many moles of KCl are produced when 2 moles of K react with 2 moles of Cl2?
-
A.
1 mole
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B.
2 moles
-
C.
3 moles
-
D.
4 moles
Solution
The balanced equation is 2K + Cl2 → 2KCl. Therefore, 2 moles of K will produce 2 moles of KCl.
Correct Answer: B — 2 moles
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Q. How many moles of NaOH are produced when 2 moles of Na react with 2 moles of water?
-
A.
1 mole
-
B.
2 moles
-
C.
3 moles
-
D.
4 moles
Solution
2Na + 2H2O → 2NaOH. Therefore, 2 moles of Na produce 2 moles of NaOH.
Correct Answer: B — 2 moles
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