Describe some ways you could keep ice from melting over a long period of time?
1 answer:
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Answer:
(a) 0.779 mol Cr₂O₃
(b) 118 g Cr₂O₃
Explanation:
Step 1: Convert 156 g Cr₂S₃ to moles
Cr Molar Mass - 52.00 g/mol × 2 = 104.00 g/mol
S Molar Mass - 32.07 g/mol × 3 = 96.21 g/mol
156 g Cr₂S₃ ÷ 200.21 g/mol = 0.779182 mol Cr₂S₃
Step 2: Find conversion from Cr₂S₃ to Cr₂O₃
1 mol Cr₂S₃ equals 1 mol Cr₂O₃
Step 3: Use Dimensional Analysis
0.779182 mol Cr₂S₃ · = 0.779182 mol Cr₂O₃
0.779182 mol Cr₂O₃ ≈ 0.779 mol Cr₂O₃ (3 significant figures)
Step 4: Convert moles to grams
Cr Molar Mass - 52.00 g/mol × 2 = 104.00 g/mol
O Molar Mass - 16.00 g/mol × 3 = 48.00 g/mol
0.779182 mol Cr₂O₃ · 152.00 g/mol = 118.436 g Cr₂O₃
118.436 g Cr₂O₃ ≈ 118 g Cr₂O₃ (3 significant figures)
Answer:
1.5 x 10²²atoms
Explanation:
Given parameters:
Mass of Br = 1.98g
Unknown:
Number of atoms
Solution:
A mole of a substance is the amount of substance contained in the avogadro's number of particles.
To solve this problem, we must first find the number of moles present in the given mass of the Br atom:
Number of moles = =
= 0.025mole.
Now we know that:
1 mole = 6.02 x 10²³
0.025 mole = 0.025 x 6.02 x 10²³ = 1.5 x 10²²atoms