Calculate the moles of solute dissolved in 4.2 dm3 of a 0.5 mol / dm3 solution.

Question

Calculate the moles of solute dissolved in 4.2 dm3 of a 0.5 mol / dm3 solution.

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Adela 4 years 2021-07-12T17:26:49+00:00 1 Answers 51 views 0

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  1. Sapo1
    1
    2021-07-12T17:28:28+00:00
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    Answer:

    Example

    0.5 mol of sodium hydroxide is dissolved in 2 dm3 of water. Calculate the concentration of the sodium hydroxide solution formed.

    Concentration =

    Concentration = 0.25 mol/dm3

    Volume units

    Volumes used in concentration calculations must be in dm3, not in cm3. It is useful to know that 1 dm3 = 1000 cm3. This means:

    divide by 1000 to convert from cm3 to dm3

    multiply by 1000 to convert from dm3 to cm3

    For example, 250 cm3 is 0.25 dm3 (250 ÷ 1000). It is often easiest to convert from cm3 to dm3 before continuing with a concentration calculation.

    Question

    100 cm3 of dilute hydrochloric acid contains 0.02 mol of dissolved hydrogen chloride. Calculate the concentration of the acid in mol/dm3.

    Reveal answer

    Converting between units

    The relative formula mass of the solute is used to convert between mol/dm3 and g/dm3:

    to convert from mol/dm3 to g/dm3, multiply by the relative formula mass

    to convert from g/dm3 to mol/dm3, divide by the relative formula mass

    Remember: the molar mass is the Ar or Mr in grams per mol.

    Example

    Calculate the concentration of 0.1 mol/dm3 sodium hydroxide solution in g/dm3. (Mr of NaOH = 40)

    Concentration = 0.1 × 40

    = 4 g/dm3

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Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )