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1. How many moles of the substance are in the following amounts? a) 2.50 g of lead b) 5.00 g of KBr c) 3.75 g of Ca3(PO4)2 d) 10.00 g of CH₂CH₂CH₂CH₂CH₂CH3 e) 15.00 g of CuSO 5 H₂O f) a cube of copper metal with an edge length of 1.00 in. The density of copper is 8.92 g/cm³ solve it properly srep by step cancellation by cancellation
Accepted Answer
Here's how to calculate the moles of each substance, step-by-step, with cancellations:
a) 2.50 g of lead (Pb)
Molar mass of Pb: 207.2 g/mol
Calculation:
2.50 g Pb
(1 mol Pb / 207.2 g Pb) = 0.0121 mol Pb
b) 5.00 g of KBr
Molar mass of KBr: 119.0 g/mol
Calculation:
5.00 g KBr
(1 mol KBr / 119.0 g KBr) = 0.0420 mol KBr
c) 3.75 g of Ca₃(PO₄)₂
Molar mass of Ca₃(PO₄)₂: 310.18 g/mol
Calculation:
3.75 g Ca₃(PO₄)₂
(1 mol Ca₃(PO₄)₂ / 310.18 g Ca₃(PO₄)₂) = 0.0121 mol Ca₃(PO₄)₂
d) 10.00 g of CH₂CH₂CH₂CH₂CH₂CH₃ (Hexane)
Molar mass of Hexane: 86.18 g/mol
Calculation:
10.00 g C₆H₁₄
(1 mol C₆H₁₄ / 86.18 g C₆H₁₄) = 0.116 mol C₆H₁₄
e) 15.00 g of CuSO₄·5H₂O (Copper(II) Sulfate Pentahydrate)
Molar mass of CuSO₄·5H₂O: 249.68 g/mol
Calculation:
15.00 g CuSO₄·5H₂O
(1 mol CuSO₄·5H₂O / 249.68 g CuSO₄·5H₂O) = 0.0601 mol CuSO₄·5H₂O
f) Cube of copper with edge length 1.00 in.
Convert inches to cm: 1.00 in
(2.54 cm / 1 in) = 2.54 cm
Calculate volume: (2.54 cm)³ = 16.4 cm³
Calculate mass: 16.4 cm³
(8.92 g / cm³) = 146 g
Molar mass of Cu: 63.55 g/mol
Calculation:
146 g Cu
(1 mol Cu / 63.55 g Cu) = 2.30 mol Cu
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