Question

name: 9) how many moles are present in 34 grams of cu(oh)₂? 10) how many moles are present in 2.45 grams of na₂o? 11) how many grams are there in 3.4 moles of nh₃? 12) how much does 4.2 moles of ca(no₃)₂ weigh? 13) how much does 3.8 moles of mgo weigh? 14) how many moles are present in 34 grams of ba(no₃)₂? 15) how many moles are present in 2.45 grams of ch₄? 16) how many grams are there in 6.7 moles of cl₂? 17) how much does 4.2 moles of al₂(so₄)₃ weigh?

Explanation:

Step1: Calculate molar mass of \(Cu(OH)_2\)

Atomic masses: \(Cu = 63.55\space g/mol\), \(O = 16\space g/mol\), \(H = 1.01\space g/mol\)
Molar mass \(M=63.55+(16 + 1.01)\times2=63.55 + 34.02=97.57\space g/mol\)

Step2: Calculate moles using \(n=\frac{m}{M}\)

Given \(m = 34\space g\), \(n=\frac{34}{97.57}\approx0.35\space mol\)

Step1: Calculate molar mass of \(Na_2O\)

Atomic masses: \(Na = 22.99\space g/mol\), \(O = 16\space g/mol\)
Molar mass \(M = 2\times22.99+16=45.98 + 16=61.98\space g/mol\)

Step2: Calculate moles using \(n=\frac{m}{M}\)

Given \(m = 2.45\space g\), \(n=\frac{2.45}{61.98}\approx0.04\space mol\)

Step1: Calculate molar mass of \(NH_3\)

Atomic masses: \(N = 14.01\space g/mol\), \(H = 1.01\space g/mol\)
Molar mass \(M=14.01+1.01\times3=14.01 + 3.03=17.04\space g/mol\)

Step2: Calculate mass using \(m=n\times M\)

Given \(n = 3.4\space mol\), \(m=3.4\times17.04 = 57.94\space g\)

Step1: Calculate molar mass of \(Ca(NO_3)_2\)

Atomic masses: \(Ca = 40.08\space g/mol\), \(N = 14.01\space g/mol\), \(O = 16\space g/mol\)
\(M=40.08+(14.01 + 16\times3)\times2=40.08+(14.01+48)\times2=40.08 + 124.02=164.1\space g/mol\)

Step2: Calculate mass using \(m=n\times M\)

Given \(n = 4.2\space mol\), \(m=4.2\times164.1 = 689.22\space g\)

Answer:

\(0.35\space mol\)