Solutions

The Fixer (rescue a weigh-out): practice problems

Work out the result for the Fixer (rescue a weigh-out). Every answer here is computed by the same tested calculator the rest of the site uses, so a solution can never drift away from the maths.

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Problem 1 The Fixer (rescue a weigh-out)

Work out the result for the Fixer (rescue a weigh-out).

  • Mass you actually weighed (mg): 400
  • Molar mass (g/mol): 58.44
  • Target concentration (M): 0.1
Show the answer and the working

Dissolve it in 68.446 mL to get 0.1 M.

  1. Moles in hand: mass / MW = 6.845 mmol
  2. Dissolve to: n / c_target = 68.446 mL

Open this in the calculator to change the numbers.

Problem 2 The Fixer (rescue a weigh-out)

Work out the result for the Fixer (rescue a weigh-out).

  • Mass you actually weighed (mg): 112
  • Molar mass (g/mol): 58.44
  • Target concentration (M): 0.1
Show the answer and the working

Dissolve it in 19.165 mL to get 0.1 M.

  1. Moles in hand: mass / MW = 1.916 mmol
  2. Dissolve to: n / c_target = 19.165 mL

Open this in the calculator to change the numbers.

Problem 3 The Fixer (rescue a weigh-out)

Work out the result for the Fixer (rescue a weigh-out).

  • Mass you actually weighed (mg): 400
  • Molar mass (g/mol): 58.44
  • Target concentration (M): 0.4
Show the answer and the working

Dissolve it in 17.112 mL to get 0.4 M.

  1. Moles in hand: mass / MW = 6.845 mmol
  2. Dissolve to: n / c_target = 17.112 mL

Open this in the calculator to change the numbers.

Problem 4 The Fixer (rescue a weigh-out)

Work out the result for the Fixer (rescue a weigh-out).

  • Mass you actually weighed (mg): 500
  • Molar mass (g/mol): 58.44
  • Target concentration (M): 0.4
Show the answer and the working

Dissolve it in 21.389 mL to get 0.4 M.

  1. Moles in hand: mass / MW = 8.556 mmol
  2. Dissolve to: n / c_target = 21.389 mL

Open this in the calculator to change the numbers.

Problem 5 The Fixer (rescue a weigh-out)

Work out the result for the Fixer (rescue a weigh-out).

  • Mass you actually weighed (mg): 300
  • Molar mass (g/mol): 58.44
  • Target concentration (M): 0.4
Show the answer and the working

Dissolve it in 12.834 mL to get 0.4 M.

  1. Moles in hand: mass / MW = 5.133 mmol
  2. Dissolve to: n / c_target = 12.834 mL

Open this in the calculator to change the numbers.

Problem 6 The Fixer (rescue a weigh-out)

Work out the result for the Fixer (rescue a weigh-out).

  • Mass you actually weighed (mg): 112
  • Molar mass (g/mol): 58.44
  • Target concentration (M): 0.75
Show the answer and the working

Dissolve it in 2.555 mL to get 0.75 M.

  1. Moles in hand: mass / MW = 1.916 mmol
  2. Dissolve to: n / c_target = 2.555 mL

Open this in the calculator to change the numbers.

Problem 7 The Fixer (rescue a weigh-out)

Work out the result for the Fixer (rescue a weigh-out).

  • Mass you actually weighed (mg): 100
  • Molar mass (g/mol): 58.44
  • Target concentration (M): 0.25
Show the answer and the working

Dissolve it in 6.845 mL to get 0.25 M.

  1. Moles in hand: mass / MW = 1.711 mmol
  2. Dissolve to: n / c_target = 6.845 mL

Open this in the calculator to change the numbers.

Problem 8 The Fixer (rescue a weigh-out)

Work out the result for the Fixer (rescue a weigh-out).

  • Mass you actually weighed (mg): 112
  • Molar mass (g/mol): 58.44
  • Target concentration (M): 0.15
Show the answer and the working

Dissolve it in 12.777 mL to get 0.15 M.

  1. Moles in hand: mass / MW = 1.916 mmol
  2. Dissolve to: n / c_target = 12.777 mL

Open this in the calculator to change the numbers.

Problem 9 The Fixer (rescue a weigh-out)

Work out the result for the Fixer (rescue a weigh-out).

  • Mass you actually weighed (mg): 150
  • Molar mass (g/mol): 58.44
  • Target concentration (M): 0.1
Show the answer and the working

Dissolve it in 25.667 mL to get 0.1 M.

  1. Moles in hand: mass / MW = 2.567 mmol
  2. Dissolve to: n / c_target = 25.667 mL

Open this in the calculator to change the numbers.

Problem 10 The Fixer (rescue a weigh-out)

Work out the result for the Fixer (rescue a weigh-out).

  • Mass you actually weighed (mg): 300
  • Molar mass (g/mol): 58.44
  • Target concentration (M): 0.1
Show the answer and the working

Dissolve it in 51.335 mL to get 0.1 M.

  1. Moles in hand: mass / MW = 5.133 mmol
  2. Dissolve to: n / c_target = 51.335 mL

Open this in the calculator to change the numbers.

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