10. how many molecules are in 0.002 mol of h₂o?\n11. what is the mass of 2.00 mol of h₂o?\n12. how many…

Explanation:

Step1: Recall Avogadro's number

Avogadro's number $N_A = 6.022\times10^{23}$ molecules/mol.

Step2: Calculate number of molecules

The number of molecules $n$ of $H_2O$ with amount of substance $n_{substance}=0.002\ mol$ is given by $n = n_{substance}\times N_A$. $n=0.002\ mol\times6.022\times10^{23}$ molecules/mol $ = 1.2044\times 10^{21}$ molecules.

Answer:

$1.2044\times 10^{21}$ molecules

Explanation:

Step1: Find molar - mass of $H_2O$

The molar - mass of $H_2O$, $M=(2\times1.01 + 16.00)\ g/mol=18.02\ g/mol$.

Step2: Calculate mass

The mass $m$ of $2.00\ mol$ of $H_2O$ is $m = n\times M$, where $n = 2.00\ mol$ and $M = 18.02\ g/mol$. $m=2.00\ mol\times18.02\ g/mol = 36.04\ g$.

Answer:

$36.04\ g$

Explanation:

Step1: Find molar - mass of $CO_2$

The molar - mass of $CO_2$, $M=(12.01+2\times16.00)\ g/mol = 44.01\ g/mol$.

Step2: Calculate mass

The mass $m$ of $3.50\ mol$ of $CO_2$ is $m=n\times M$, where $n = 3.50\ mol$ and $M = 44.01\ g/mol$. $m=3.50\ mol\times44.01\ g/mol=154.035\ g$.

Answer:

$154.035\ g$

Explanation:

Step1: Find molar - mass of $NaCl$

The molar - mass of $NaCl$, $M=(22.99 + 35.45)\ g/mol=58.44\ g/mol$.

Step2: Calculate mass

The mass $m$ of $1.25\ mol$ of $NaCl$ is $m=n\times M$, where $n = 1.25\ mol$ and $M = 58.44\ g/mol$. $m=1.25\ mol\times58.44\ g/mol = 73.05\ g$.

Answer:

$73.05\ g$

Explanation:

Step1: Find molar - mass of $CO_2$

The molar - mass of $CO_2$, $M=(12.01 + 2\times16.00)\ g/mol=44.01\ g/mol$.

Step2: Calculate number of moles

The number of moles $n$ of $CO_2$ with mass $m = 88.0\ g$ is $n=\frac{m}{M}$. $n=\frac{88.0\ g}{44.01\ g/mol}\approx2.00\ mol$.

Answer:

$2.00\ mol$

Explanation:

Step1: Find molar - mass of $CH_4O$

The molar - mass of $CH_4O$, $M=(12.01+4\times1.01 + 16.00)\ g/mol=32.05\ g/mol$.

Step2: Calculate mass

The mass $m$ of $0.250\ mol$ of $CH_4O$ is $m=n\times M$, where $n = 0.250\ mol$ and $M = 32.05\ g/mol$. $m=0.250\ mol\times32.05\ g/mol = 8.0125\ g$.

Answer:

$8.0125\ g$

Explanation:

Step1: Find molar - mass of $NH_3$

The molar - mass of $NH_3$, $M=(14.01+3\times1.01)\ g/mol = 17.04\ g/mol$.

Step2: Calculate mass

The mass $m$ of $0.60\ mol$ of $NH_3$ is $m=n\times M$, where $n = 0.60\ mol$ and $M = 17.04\ g/mol$. $m=0.60\ mol\times17.04\ g/mol=10.224\ g$.

Answer:

$10.224\ g$

Explanation:

Step1: Find molar - mass of $Fe$

The molar - mass of $Fe$, $M = 55.85\ g/mol$.

Step2: Calculate mass

The mass $m$ of $4.00\ mol$ of $Fe$ is $m=n\times M$, where $n = 4.00\ mol$ and $M = 55.85\ g/mol$. $m=4.00\ mol\times55.85\ g/mol=223.4\ g$.

Answer:

$223.4\ g$

Explanation:

Step1: Find molar - mass of $H_2O$

The molar - mass of $H_2O$, $M=(2\times1.01+16.00)\ g/mol = 18.02\ g/mol$.

Step2: Calculate number of moles

The number of moles $n$ of $H_2O$ with mass $m = 120\ g$ is $n=\frac{m}{M}$. $n=\frac{120\ g}{18.02\ g/mol}\approx6.66\ mol$.

Answer:

$6.66\ mol$

Explanation:

Step1: Find molar - mass of $NaCl$

The molar - mass of $NaCl$, $M=(22.99+35.45)\ g/mol = 58.44\ g/mol$.

Step2: Calculate number of moles

The number of moles $n$ of $NaCl$ with mass $m = 127.1\ g$ is $n=\frac{m}{M}$. $n=\frac{127.1\ g}{58.44\ g/mol}\approx2.18\ mol$.

Answer:

$2.18\ mol$

Explanation:

Step1: Find molar - mass of $Mg(OH)_2$

The molar - mass of $Mg(OH)_2$, $M=(24.31+2\times(16.00 + 1.01))\ g/mol=(24.31+2\times17.01)\ g/mol=58.33\ g/mol$.

Step2: Calculate mass

The mass $m$ of $0.75\ mol$ of $Mg(OH)_2$ is $m=n\times M$, where $n = 0.75\ mol$ and $M = 58.33\ g/mol$. $m=0.75\ mol\times58.33\ g/mol = 43.7475\ g$.

Answer:

$43.7475\ g$