Home Chemistry 3 – Molar Solutions

Last year, I had a go at preparing a known concentration 1M of Sodium Chloride (Salt). Using the instructions at Quora.

• How many grams of sodium chloride are required to prepare 250 mL of a solution of 1M sodium chloride?

In order to some chemicals for future use. I will use the same instructions to create a known concentration of Citric Acid, given I want to test the reactivity between this and various metals, in a similar way to my previous experiment in Home Chemistry 1

Calculations

1. Decide how much solution is needed – 250ml
2. Determine Molar mass of Citric Acid
   • According to PubChem this is 192.12g
3. Work out how much solid powder is needed
   • Given 1 Mol is the molecular weight in 1 litire of water
4. We are producing 250ml – so need to weigh out ¼ of the molar mass
   • 192.12 / 4 = 48.03g
5. So based on the instructions I found for NaCl
6. We need to dissolve 48.03g in 250ml of Water to produce 250ml 1 molar concentration of Citric Acid

Safety

1. Refer to data sheet – We know that Citric Acid is a Irritant, therefore it would be prudent to stick the CORRECT label on the bottle storing the solution.
2. Correctly label the bottle
3. Wear goggles when preparing the solution
4. Wear gloves and Lab Coat
5. Clean Surfaces
6. Wash hands when finished

Equipment

• Scales or Balance
• Volumetric Flask *1
• Stirrer
• Spatula
• Paper to write notes
• Paper to put on scales for powder
• Funnel
• Label saying 250ml 1 mol Citric Acid
• Label giving formula and Molar weight
• Irritant label

Equipment Replacement

*1 As I don't have a volumetric Flask, I can use a 250 or 500ml Conical Flask

Considerations

My weighing scales are only basic and do not measure to 2 decimal places, there for we can weigh out 48g. As this is for home chemistry, while accuracy is important, we can probably make minor compromises.

Chemicals

• Water
• Citric Acid Powder

Method

Read fully first

1. Prepare equipment
2. Measure out 250ml Water
3. Fold paper in ½
4. Unfold paper
5. Put paper on scales
6. Ensure Scales are ZERO
7. Weigh out required amount of Citric Acid Powder
8. Pour powder in to flask and stir or move flask around in a circular motion*
9. Pour solution in to suitable container
10. Stick on labels
11. Wash up and dry equipment
12. Wipe down surfaces etc
13. Wash hands
14. Store solution safely

Note the fold in the paper,just makes this easier.

• You may need to pour small amounts in to the flash, and dissolve before adding more

Further reading and advice

There will be a related thread on Science Forums for this, as I want to double check everything is correct.

Tags

#Home,#Chemistry,#HomeChemistry3,#Molar,#Solution,#CitricAcid

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