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Home Q & A Board Science-Related Homework Help Chemistry (Moderator: Laser_3)
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NWCH NWCH
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10 years ago
I am having trouble solving this chemistry problem and would appreciate it if someone could tell me how to solve this problem step by step. Thanks!!

What is the molality of particles in a solution containing 15.1g of KBr disolved in 780g of water?
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10 years ago
15.1g/molar mass of KBr and then divide it by 0.780 kg water

answer mine?
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tony51092tony51092
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10 years ago
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1.  Find molar mass, then divide mass by molar mass.
K = 39.10 g.mol
Br = 79.90 g.mol
Molar mass: 39.10 g/mol + 79.90 g.mol = 119 g.mol

2.  Divide mass by molar mass to get moles:
n = m / M, where n = moles, m = mass, M = molar mass
n = 15.1 g / 119 g/mol = 0.126

3.  Molality is the moles solute divided by kilograms solvent.
m = 0.126 mol / 0.780 kg = 0.162 molal
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