mass and the mole
1) how many moles are in 15 grams of lithium?
2) how many grams are in 2.4 moles of sulfur?
3) how many moles are in 22 grams of argon?
4) how many grams are in 88.1 moles of magnesium?
5) how many moles are in 2.3 grams of phosphorus?
6) how many grams are in 11.9 moles of chromium?
7) how many moles are in 9.8 grams of calcium?
8) how many grams are in 238 moles of arsenic?
what are the molecular weights of the following compounds?
9) naoh
12) h₃po₄
10) h₂o
13) mn₂se₇
11) mgcl₂
14) (nh₄)₂so₄

Question

Accepted Answer

### Problem 1: How many moles are in 15 grams of lithium?
# Explanation:
## Step1: Recall the molar mass of Li.
The molar mass of Li (lithium) is approximately $ 6.94 \, \text{g/mol} $.
## Step2: Use the formula $ \text{moles} = \frac{\text{mass}}{\text{molar mass}} $.
Substitute the given mass ($ 15 \, \text{g} $) and molar mass ($ 6.94 \, \text{g/mol} $) into the formula:
$ \text{moles} = \frac{15}{6.94} \approx 2.16 \, \text{moles} $.
# Answer:
Approximately $ 2.16 $ moles.

### Problem 2: How many grams are in 2.4 moles of sulfur?
# Explanation:
## Step1: Recall the molar mass of S.
The molar mass of S (sulfur) is approximately $ 32.07 \, \text{g/mol} $.
## Step2: Use the formula $ \text{mass} = \text{moles} \times \text{molar mass} $.
Substitute the given moles ($ 2.4 \, \text{mol} $) and molar mass ($ 32.07 \, \text{g/mol} $):
$ \text{mass} = 2.4 \times 32.07 \approx 76.97 \, \text{grams} $.
# Answer:
Approximately $ 77.0 $ grams (or $ 76.97 $ grams).

### Problem 3: How many moles are in 22 grams of argon?
# Explanation:
## Step1: Recall the molar mass of Ar.
The molar mass of Ar (argon) is approximately $ 39.95 \, \text{g/mol} $.
## Step2: Use the formula $ \text{moles} = \frac{\text{mass}}{\text{molar mass}} $.
Substitute the given mass ($ 22 \, \text{g} $) and molar mass ($ 39.95 \, \text{g/mol} $):
$ \text{moles} = \frac{22}{39.95} \approx 0.551 \, \text{moles} $.
# Answer:
Approximately $ 0.55 $ moles (or $ 0.551 $ moles).

### Problem 4: How many grams are in 88.1 moles of magnesium?
# Explanation:
## Step1: Recall the molar mass of Mg.
The molar mass of Mg (magnesium) is approximately $ 24.31 \, \text{g/mol} $.
## Step2: Use the formula $ \text{mass} = \text{moles} \times \text{molar mass} $.
Substitute the given moles ($ 88.1 \, \text{mol} $) and molar mass ($ 24.31 \, \text{g/mol} $):
$ \text{mass} = 88.1 \times 24.31 \approx 2142 \, \text{grams} $ (or $ 2140 \, \text{g} $ for simplicity).
# Answer:
Approximately $ 2140 $ grams (or $ 2142 $ grams).

### Problem 5: How many moles are in 2.3 grams of phosphorus?
# Explanation:
## Step1: Recall the molar mass of P.
The molar mass of P (phosphorus) is approximately $ 30.97 \, \text{g/mol} $.
## Step2: Use the formula $ \text{moles} = \frac{\text{mass}}{\text{molar mass}} $.
Substitute the given mass ($ 2.3 \, \text{g} $) and molar mass ($ 30.97 \, \text{g/mol} $):
$ \text{moles} = \frac{2.3}{30.97} \approx 0.0743 \, \text{moles} $.
# Answer:
Approximately $ 0.074 $ moles (or $ 0.0743 $ moles).

### Problem 6: How many grams are in 11.9 moles of chromium?
# Explanation:
## Step1: Recall the molar mass of Cr.
The molar mass of Cr (chromium) is approximately $ 52.00 \, \text{g/mol} $.
## Step2: Use the formula $ \text{mass} = \text{moles} \times \text{molar mass} $.
Substitute the given moles ($ 11.9 \, \text{mol} $) and molar mass ($ 52.00 \, \text{g/mol} $):
$ \text{mass} = 11.9 \times 52.00 = 618.8 \, \text{grams} $.
# Answer:
$ 618.8 $ grams (or $ 619 $ grams).

### Problem 7: How many moles are in 9.8 grams of calcium?
# Explanation:
## Step1: Recall the molar mass of Ca.
The molar mass of Ca (calcium) is approximately $ 40.08 \, \text{g/mol} $.
## Step2: Use the formula $ \text{moles} = \frac{\text{mass}}{\text{molar mass}} $.
Substitute the given mass ($ 9.8 \, \text{g} $) and molar mass ($ 40.08 \, \text{g/mol} $):
$ \text{moles} = \frac{9.8}{40.08} \approx 0.2445 \, \text{moles} $.
# Answer:
Approximately $ 0.245 $ moles (or $ 0.2445 $ moles).

### Problem 8: How many grams are in 238 moles of arsenic?
# Explanation:
## Step1: Recall the molar mass of As.
The molar mass of As (arsenic) is approximately $ 74.92 \, \text{g/mol} $.
## Step2: Use the formula $ \text{mass} = \text{moles} \times \text{molar mass} $.
Substitute the given moles ($ 238 \, \text{mol} $) and molar mass ($ 74.92 \, \text{g/mol} $):
$ \text{mass} = 238 \times 74.92 \approx 17830 \, \text{grams} $ (or $ 1.78 \times 10^4 \, \text{g} $).
# Answer:
Approximately $ 17800 $ grams (or $ 1.78 \times 10^4 $ grams).

### Problem 9: What is the molecular weight of $ \text{NaOH} $?
# Explanation:
## Step1: Identify the atomic masses.
- Na (sodium): $ 22.99 \, \text{g/mol} $
- O (oxygen): $ 16.00 \, \text{g/mol} $
- H (hydrogen): $ 1.01 \, \text{g/mol} $
## Step2: Sum the atomic masses.
$ \text{Molecular weight} = 22.99 + 16.00 + 1.01 = 40.00 \, \text{g/mol} $.
# Answer:
$ 40.00 \, \text{g/mol} $ (or $ 40 \, \text{g/mol} $).

### Problem 10: What is the molecular weight of $ \text{H}_2\text{O} $?
# Explanation:
## Step1: Identify the atomic masses.
- H (hydrogen): $ 1.01 \, \text{g/mol} $ (2 atoms)
- O (oxygen): $ 16.00 \, \text{g/mol} $ (1 atom)
## Step2: Sum the atomic masses.
$ \text{Molecular weight} = (2 \times 1.01) + 16.00 = 2.02 + 16.00 = 18.02 \, \text{g/mol} $.
# Answer:
$ 18.02 \, \text{g/mol} $ (or $ 18 \, \text{g/mol} $).

### Problem 11: What is the molecular weight of $ \text{MgCl}_2 $?
# Explanation:
## Step1: Identify the atomic masses.
- Mg (magnesium): $ 24.31 \, \text{g/mol} $
- Cl (chlorine): $ 35.45 \, \text{g/mol} $ (2 atoms)
## Step2: Sum the atomic masses.
$ \text{Molecular weight} = 24.31 + (2 \times 35.45) = 24.31 + 70.90 = 95.21 \, \text{g/mol} $.
# Answer:
$ 95.21 \, \text{g/mol} $ (or $ 95.2 \, \text{g/mol} $).

### Problem 12: What is the molecular weight of $ \text{H}_3\text{PO}_4 $?
# Explanation:
## Step1: Identify the atomic masses.
- H (hydrogen): $ 1.01 \, \text{g/mol} $ (3 atoms)
- P (phosphorus): $ 30.97 \, \text{g/mol} $ (1 atom)
- O (oxygen): $ 16.00 \, \text{g/mol} $ (4 atoms)
## Step2: Sum the atomic masses.
$ \text{Molecular weight} = (3 \times 1.01) + 30.97 + (4 \times 16.00) $
$ = 3.03 + 30.97 + 64.00 = 98.00 \, \text{g/mol} $.
# Answer:
$ 98.00 \, \text{g/mol} $ (or $ 98 \, \text{g/mol} $).

### Problem 13: What is the molecular weight of $ \text{Mn}_2\text{Se}_7 $?
# Explanation:
## Step1: Identify the atomic masses.
- Mn (manganese): $ 54.94 \, \text{g/mol} $ (2 atoms)
- Se (selenium): $ 78.96 \, \text{g/mol} $ (7 atoms)
## Step2: Sum the atomic masses.
$ \text{Molecular weight} = (2 \times 54.94) + (7 \times 78.96) $
$ = 109.88 + 552.72 = 662.60 \, \text{g/mol} $.
# Answer:
$ 662.60 \, \text{g/mol} $ (or $ 663 \, \text{g/mol} $).

### Problem 14: What is the molecular weight of $ (\text{NH}_4)_2\text{SO}_4 $?
# Explanation:
## Step1: Identify the atomic masses.
- N (nitrogen): $ 14.01 \, \text{g/mol} $ (2 atoms)
- H (hydrogen): $ 1.01 \, \text{g/mol} $ (8 atoms, since $ 2 \times 4 = 8 $)
- S (sulfur): $ 32.07 \, \text{g/mol} $ (1 atom)
- O (oxygen): $ 16.00 \, \text{g/mol} $ (4 atoms)
## Step2: Sum the atomic masses.
$ \text{Molecular weight} = (2 \times 14.01) + (8 \times 1.01) + 32.07 + (4 \times 16.00) $
$ = 28.02 + 8.08 + 32.07 + 64.00 = 132.17 \, \text{g/mol} $.
# Answer:
$ 132.17 \, \text{g/mol} $ (or $ 132 \, \text{g/mol} $).

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QUESTION IMAGE

Question

Explanation:

Problem 1: How many moles are in 15 grams of lithium?

Step1: Recall the molar mass of Li.

Step2: Use the formula \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \).

Step1: Recall the molar mass of S.

Step2: Use the formula \( \text{mass} = \text{moles} \times \text{molar mass} \).

Step1: Recall the molar mass of Ar.

Step2: Use the formula \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \).

Answer:

Problem 2: How many grams are in 2.4 moles of sulfur?