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? asked in Science & MathematicsChemistry · 4 years ago

What is the molar concentration of ...?

The hardness of water (hardness count) is usually expressed in milligrams of CaCO3 per liter of water. What is the molar concentration of Ca2+ ions in a water sample with a hardness count of 175 mg CaCO3/L H2O? Assume the density of the solution is the same as pure water.

17.5 M

1750 M

1.75 M

There is not enough information to answer the question.

1.75 x 10-3 M

3 Answers

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  • Trevor H
    Lv 7
    4 years ago

    175 mg CaCO3/L H2O

    Molar mass Ca2+ = 40g/mol

    Molar mass CaCO3 = 100g/mol

    Mass of Ca2+ in 1.0L of water = 175*40/100 = 70mg Ca2+ in 1.0L water

    Calculate mol of Ca 2+ dissolved in 1.0L solution = 0.070g/ 40g/Mol

    mol Ca2+ = 1.75*10^-3 mol Ca2+ dissolved in 1.0L solution

    Molarity of Ca2+ = 1.75*10^-3M

  • Taslima
    4 years ago

    its the last one 1.75 x 10-3 M

  • Viviana Cantu
    4 years ago

    Lol are you in ch302 also hahahahaha I need help on this one too hahaha

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