Question

1. sodium bicarbonate (baking soda) - find the mass of a scoop of baking soda using a weighing dish.

a) calculate the number of moles in the sample.

b) calculate the number of molecules in the sample.

c) calculate the total number of atoms in the sample.

Explanation:

Step1: Calculate the molar mass of \(NaHCO_3\)

The atomic masses are: \(Na = 22.99\space g/mol\), \(H= 1.01\space g/mol\), \(C = 12.01\space g/mol\), \(O=16.00\space g/mol\)

$$M(NaHCO_3)=22.99 + 1.01+12.01+(3\times16.00)$$

$$M(NaHCO_3)=84.01\space g/mol$$

Step2: Calculate the number of moles (\(n\)) in the sample (for part a)

Using the formula \(n=\frac{m}{M}\), where \(m = 3.37\space g\) and \(M = 84.01\space g/mol\)

$$n=\frac{3.37}{84.01}\approx0.0401\space mol$$

Step3: Calculate the number of molecules (for part b)

Using the formula \(N = n\times N_A\), where \(N_A=6.022\times 10^{23}\space mol^{-1}\) and \(n = 0.0401\space mol\)

$$N=0.0401\times6.022\times 10^{23}$$

$$N = 2.415\times 10^{22}\space molecules$$

Step4: Calculate the number of atoms per molecule of \(NaHCO_3\)

In \(NaHCO_3\), there are \(1 + 1+1 + 3=6\) atoms per molecule

Step5: Calculate the total number of atoms (for part c)

Multiply the number of molecules by the number of atoms per molecule

$$N_{atoms}=2.415\times 10^{22}\times6$$

$$N_{atoms}=1.449\times 10^{23}\space atoms$$

Answer:

a) \(0.0401\space mol\)
b) \(2.415\times 10^{22}\space molecules\)
c) \(1.449\times 10^{23}\space atoms\)