Question

4 atoms w to moles w
mol w
etextbook and media
94 molecules h₂o to kg h₂o
kg h₂o

Explanation:

Step1: Convert atoms to moles

Use Avogadro's number \(N_A = 6.022\times10^{23}\text{ atoms/mol}\).
$$n=\frac{N}{N_A}$$
For \(N = 4\) atoms of \(W\),
$$n=\frac{4}{6.022\times10^{23}}$$

Step2: Calculate the value

$$n\approx6.64\times 10^{-24}\text{ mol}$$

Step3: Convert molecules of \(H_2O\) to moles

Use \(N_A = 6.022\times10^{23}\text{ molecules/mol}\).
For \(N = 94\) molecules of \(H_2O\),
$$n=\frac{94}{6.022\times10^{23}}$$

Step4: Calculate moles of \(H_2O\)

$$n\approx1.56\times 10^{-22}\text{ mol}$$

Step5: Find molar mass of \(H_2O\)

Molar mass of \(H_2O\), \(M=(2\times1 + 16)\text{ g/mol}=18\text{ g/mol}\)

Step6: Convert moles to grams

Mass \(m=n\times M\)
$$m = 1.56\times 10^{-22}\times18\text{ g}$$
$$m=2.81\times 10^{-21}\text{ g}$$

Step7: Convert grams to kilograms

Since \(1\text{ kg} = 1000\text{ g}\),
$$m=2.81\times 10^{-24}\text{ kg}$$

Answer:

For \(4\) atoms \(W\): \(6.64\times 10^{-24}\text{ mol}\)
For \(94\) molecules \(H_2O\): \(2.81\times 10^{-24}\text{ kg}\)