Question

1. brass is an alloy of copper (cu) and zinc (zn). if 8.32 g of copper is mixed with 5.2372×10⁻² mol of zinc, how many metal atoms in total are present in the brass alloy? a) 1.10×10²³ metal atoms b) 8.91×10⁻²⁴ metal atoms c) 7.88×10²² metal atoms d) 7.07×10²⁴ metal atoms e) 3.15×10²⁴ metal atoms

Explanation:

Step1: Calculate moles of copper

The molar mass of copper ($Cu$) is approximately $63.55\ g/mol$. Given the mass of copper is $8.32\ g$. Using the formula $n=\frac{m}{M}$, where $n$ is the number of moles, $m$ is the mass and $M$ is the molar mass. So, $n_{Cu}=\frac{8.32\ g}{63.55\ g/mol}\approx0.131\ mol$.

Step2: Calculate total moles of metal

The number of moles of zinc is $n_{Zn}=5.2372\times 10^{- 2}\ mol$. The total number of moles of metal in the alloy, $n_{total}=n_{Cu}+n_{Zn}=0.131\ mol + 5.2372\times 10^{-2}\ mol=0.131\ mol+0.052372\ mol = 0.183372\ mol$.

Step3: Calculate total number of atoms

Using Avogadro's number $N_A = 6.022\times 10^{23}\ atoms/mol$. The total number of metal atoms $N=n_{total}\times N_A=0.183372\ mol\times6.022\times 10^{23}\ atoms/mol\approx1.10\times 10^{23}\ atoms$.

Answer:

A. $1.10\times 10^{23}$ metal atoms