Question

1. note the mass of a copper(i) oxide formula unit in the image below. what is the mass of 8.250 moles of cu₂o?

options: 17.34 u, 17.349 g, 1.181 u, 1.181 g

1. what is the mass of 8.12 × 10²³ molecules of co₂ gas? (atomic mass of carbon = 12.011 u; oxygen = 15.999 u.)

options: 32.6 g, 44.0 g, 48.9 g, 59.3 g

Explanation:

Step1: Calculate the molar mass of \(Cu_2O\)

The atomic mass of \(Cu = 63.55\space u\), and the atomic mass of \(O=16.00\space u\).
For \(Cu_2O\), the molar mass \(M=(2\times63.55 + 16.00)\space g/mol=(127.1+16.00)\space g/mol = 143.1\space g/mol\)

Step2: Use the formula \(m = n\times M\)

Given \(n = 8.250\space mol\) and \(M = 143.1\space g/mol\)
\(m=8.250\space mol\times143.1\space g/mol\)
\(m = 8.250\times143.1\space g\)
\(m=(8 + 0.25)\times143.1\space g=(8\times143.1+0.25\times143.1)\space g=(1144.8 + 35.775)\space g = 1180.575\space g\approx1181\space g\)

Answer:

\(1181\space g\)