Question

1. using the mole weight, calculate the number of moles in each of the following. show your work!

a. 9.00 g of kcl
b. 161.8 g of naf
c. 65.0 g of al(no₃)₃
d. 100 g of co₂
e. 48 g of oxygen gas

1. using the mole weight from #1, calculate the number of grams in each of the following.

a. 0.50 mole of kcl
b. 1.25 moles of naf
c. 0.25 moles of al(no₃)₃
d. 4.5 moles of co₂
e. 3.3 moles of oxygen gas

1. calculate the number of molecules in 72 g of h₂o.

Explanation:

Step1: Calculate molar mass of KCl

The molar mass of K (potassium) is \(39.10\ g/mol\) and Cl (chlorine) is \(35.45\ g/mol\). So, molar mass of \(KCl=39.10 + 35.45=74.55\ g/mol\)

Step2: Calculate moles of KCl

Use the formula \(n=\frac{m}{M}\), where \(m = 9.00\ g\) (mass) and \(M = 74.55\ g/mol\) (molar mass). So, \(n=\frac{9.00}{74.55}\approx0.121\ mol\)

Step3: Calculate molar mass of NaF

The molar mass of Na (sodium) is \(22.99\ g/mol\) and F (fluorine) is \(19.00\ g/mol\). So, molar mass of \(NaF = 22.99+19.00 = 41.99\ g/mol\)

Step4: Calculate moles of NaF

Use the formula \(n=\frac{m}{M}\), where \(m = 161.8\ g\) and \(M = 41.99\ g/mol\). So, \(n=\frac{161.8}{41.99}\approx3.85\ mol\)

Step5: Calculate molar mass of \(Al(NO_3)_3\)

The molar mass of Al (aluminum) is \(26.98\ g/mol\), N (nitrogen) is \(14.01\ g/mol\), O (oxygen) is \(16.00\ g/mol\).
\(M=26.98+3\times(14.01 + 3\times16.00)=26.98+3\times(14.01+48.00)=26.98+3\times62.01=26.98 + 186.03=213.01\ g/mol\)

Step6: Calculate moles of \(Al(NO_3)_3\)

Use the formula \(n=\frac{m}{M}\), where \(m = 65.0\ g\) and \(M = 213.01\ g/mol\). So, \(n=\frac{65.0}{213.01}\approx0.305\ mol\)

Step7: Calculate molar mass of \(CO_2\)

The molar mass of C (carbon) is \(12.01\ g/mol\) and O (oxygen) is \(16.00\ g/mol\). So, molar mass of \(CO_2=12.01+2\times16.00 = 44.01\ g/mol\)

Step8: Calculate moles of \(CO_2\)

Use the formula \(n=\frac{m}{M}\), where \(m = 100\ g\) and \(M = 44.01\ g/mol\). So, \(n=\frac{100}{44.01}\approx2.27\ mol\)

Step9: Calculate molar mass of \(O_2\)

The molar mass of O (oxygen) is \(16.00\ g/mol\). So, molar mass of \(O_2 = 2\times16.00=32.00\ g/mol\)

Step10: Calculate moles of \(O_2\)

Use the formula \(n=\frac{m}{M}\), where \(m = 48\ g\) and \(M = 32.00\ g/mol\). So, \(n=\frac{48}{32.00}=1.5\ mol\)

Answer:

a. Approximately \(0.121\ mol\)
b. Approximately \(3.85\ mol\)
c. Approximately \(0.305\ mol\)
d. Approximately \(2.27\ mol\)
e. \(1.5\ mol\)