Answer:
1.75 × 10⁻³ M
Explanation:
Given:
Hardness = 175 mg CaCO₃/L
or mass of CaCO₃ in 1 L = 175 × 10⁻³ grams
Now,
Molar mass of CaCO₃ = 40 + 12 + ( 3 × 12 ) = 100 grams/mol
The concentration of CaCO₃ = number of moles / volume
or
= (175 × 10⁻³ / 100) / 1
= 1.75 × 10⁻³ M
CaCO₃ ⇒ Ca²⁺ + CO₃²⁻
1.75 × 10⁻³ M 1.75 × 10⁻³ M 1.75 × 10⁻³ M
thus,
the concentration of Ca²⁺ ions in water = 1.75 × 10⁻³ M
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"Earth-centered," or "geocentric" Ptolemy thought that all celestial objects — including the planets, Sun, Moon, and stars — orbited Earth. Earth, in the center of the universe, did not move at all.