Question

calculate the number of grams contained in 3.20 moles of rubidium dichromate - rb₂cr₂o₇. include the units, but do not write the chemical formula. round the answer to 3 significant figures. answer:

Explanation:

Step1: Calculate molar mass of \( Rb_2Cr_2O_7 \)

Molar mass of \( Rb \): \( 85.47 \, g/mol \), \( Cr \): \( 52.00 \, g/mol \), \( O \): \( 16.00 \, g/mol \)
Molar mass \( = 2\times85.47 + 2\times52.00 + 7\times16.00 \)
\( = 170.94 + 104.00 + 112.00 = 386.94 \, g/mol \)

Step2: Calculate mass from moles

Mass \( = \) moles \( \times \) molar mass
\( = 3.20 \, mol \times 386.94 \, g/mol \)
\( = 1238.208 \, g \)

Step3: Round to 3 significant figures

\( 1238.208 \, g \approx 1240 \, g \) (or \( 1.24 \times 10^3 \, g \))

Answer:

\( 1240 \, grams \) (or \( 1.24 \times 10^3 \, g \))