Q: Which of the following best defines a mole in chemistry?

A mole is a collection of $6.022 \times 10^{23}$ particles.

Q: Which conversion factor is used to relate the number of moles of a gas to its volume at STP?

$1 \text{ mol} = 22.4 \text{ L}$

Question 1

Which of the following best defines a mole in chemistry?

Accepted Answer

A mole is a collection of $6.022 	imes 10^{23}$ particles.

Question 2

The term 'atoms' is used when discussing ________, while 'molecules' is used when discussing ________.

Accepted Answer

elements; compounds

Question 3

How many formula units of $K_2P$ are there in $4.00$ mol?

Accepted Answer

$2.41 	imes 10^{24}$

Question 4

A titanium rod contains $2.86 	imes 10^{24}$ atoms. How many moles of titanium atoms are in the rod?

Accepted Answer

$4.75$ mol

Question 5

What is the molar mass of $K_2Cr_2O_7$?

Accepted Answer

$294.18$ g/mol

Question 6

How many moles are in $325$ grams of $C_7H_8O_2$? (Molar mass = $124$ g/mol)

Accepted Answer

$2.62$ mol

Question 7

How many grams are found in $5.00$ mol of $CO_2$? (Molar mass = $44.01$ g/mol)

Accepted Answer

$220.05$ g

Question 8

A solution is prepared by mixing $25.0$ g of water, $10.0$ g of ethanol, and $25.0$ g of $C_7H_8O_2$. What is the mole fraction of ethanol in this mixture? (Molar mass of ethanol = $46.07$ g/mol)

Accepted Answer

$0.15$

Question 9

What is the volume occupied by $9.3$ moles of methane gas at STP?

Accepted Answer

$208$ L

Question 10

How many moles are in $2.3 	imes 10^{24}$ molecules of oxygen gas at STP?

Accepted Answer

$3.82$ mol

Question 11

A balloon contains $8.50$ L of neon gas at STP. How many atoms of neon are in the balloon?

Accepted Answer

$2.29 	imes 10^{23}$

Question 12

Determine the volume of $14$ g of nitrogen dioxide ($NO_2$) at STP. (Molar mass = $46.01$ g/mol)

Accepted Answer

$6.81$ L

Question 13

What is the mass of $2.5 	imes 10^{23}$ atoms of tungsten? (Atomic mass = $183.84$ g/mol)

Accepted Answer

$76.4$ g

Question 14

Which of the following is the correct formula for calculating the mole fraction of component A in a mixture?

Accepted Answer

$X_A = \frac{n_A}{n_{total}}$

Question 15

At STP, what is the volume occupied by $1$ mole of any ideal gas?

Accepted Answer

$22.4$ L

Question 16

If $100.0$ g of NaCl is dissolved into $100.0$ g of pure H$_2$O$, what is the mole fraction of NaCl? (Molar mass NaCl = $58.44$ g/mol, Molar mass H$_2$O = $18.02$ g/mol)

Accepted Answer

$0.24$

Question 17

Which conversion factor is used to relate the number of moles of a gas to its volume at STP?

Accepted Answer

$1 	ext{ mol} = 22.4 	ext{ L}$

Question 18

The molar mass of a compound is found by:

Accepted Answer

Adding up the masses of the individual elements in the compound.

Question 19

Which scientist is the mole named in honor of?

Accepted Answer

Amedeo Avogadro

The Mole Concept and Molar Calculations in Chemistry

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