Home Chemistry 19 part 1

How to calculate what is needed for a displacement reaction to take place.

I asked this on Science forums but this is the basis of my question

I have some Copper Sulfate in solution, along with various metallic elements which should produce a displacement reaction for example

Rough equations@-

• CuSO_4 + Mg => MgSO4 + Cu
• CuSO_4 + Zn => ZnSO4 + Cu
• CuSO_4 + Al => AlSO4 + Cu

If I make up a 0.1 molar solution of Copper Sulfate at 100ml volume I need 2.49g of Copper Sulfate in 100ml water. This is fine.

Now if I wanted to add just enough of one of the above metals to displace all the copper do I calculate as follows

( I could look this up, but I have an idea of how to do this, so am asking to see if I am on the right track)

• 1 M of Copper sulfate weighs 249g
• Mass of copper is 63.54 g then calculating the % composition gives
  • 63.54 / 249 = 0.26 x 100 = 26%

So if I have a 0.1 M solution, and used 2.49 g of the copper sulfate do I then work out what 26% of that is with

• 0.26 x 2.49 = 0.65g

Therefore I need 0.65g of one of the above elements to displace the Copper

I think that I am nearly there with this, but given Magnesium , Aluminium and Zinc all have different weights, do I need to factor in the atomic mass of the element I am using for the displacement ?

Or just weigh out say 0.65g of Magnesium to produce

CuSO4 5H2O (solution) + Mg = MgSO4 (solution) + Cu + H20

I am not quite sure what happens to the 5H_2O here.

Am I right on my thinking here ?

• Science forum question

#Chemistry,#HomeChemistry,#HomeChemistry19

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Home Chemistry 18

I have had another go at growing salt crystals. This time I dissolved a quantity of pure Sodium Chloride (NaCl) in to water using a conical flask, then poured this solution in to a glass dish and left for about 2/3 weeks.

Eventually all the water evaporated away, leaving crystals behind. Using my USB microscope, I found and took a picture of some that had grown in to a nice cube shape.

Update 29/7/2023

I have taken another photo using the USB Microscope and also included the calibration / measurement sheet in the photo to try and illustrate crystal size.

Please see Mastodon post for details.

Tags

#Chemistry,#HomeChemistry,#HomeChemistry18,#science,#physics,#biology

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Home Chemistry 17

Periodic table properties explorer

#Chemistry,#HomeChemistry,#HomeChemistry17,#science,#physics,#biology

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Home Chemistry 16

Updated 6/8/2023

Now that I have a new batch of Red Cabbage indicator. I would like to investigate some of the chemistry of a recently collected sample of seawater, specifically the following:-

• The pH of seawater.
  
  • Video
• If adding eggshells changes the pH.

Background to this

Eggshell, contains Calcium Carbonate $\ce{CaCO3}$ when added to vinegar $\ce{CH3COOH}$ the pH value increases.

Related information

• Chemistry of egg and eggshells

Adding eggshell to vinegar increases the pH of the vinegar. I will write up my experiment / results and share this. What I want to know is can eggshell do the same to seawater.

This may be a possible solution to ocean acidification.

Links

• Science Forums

Write-up

You can find my write up for this experiment in PDF here. You may want to right click and download, otherwise it will probably just open in a browser. Provided as-is, but it should cover what I did, my results and conclusion.

Tags

#Chemistry,#HomeChemistry,#HomeChemistry16,#Science,#Seawater,#pH,#Investigation

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Home Chemistry 15

The red cabbage indicator that I am using works fine. However it looks rather red, further investigation and starting discussion on Science Forums about this, suggested a cause and solution.

In essence the indicator is acidic, hence the read colour rather than the purple neutral colour.

I have now made up a new batch, which looks a lot better

The image above illustrates the old indicator on the right hand side, the new is in the beaker on the left. You can see quite a big difference in colour.

I have extracted the pH colour scale from the original infographic below

Video

There is a 3 min Video here that I made while making the new batch of indicator up.

• Add hot water to beaker
• Add red cabbage to water
• Mix (until water is the required purple colour)
• All to cool
• Add to regent bottle

Created more indicator as required.

Discussion

• Science Forum, discussion

Tags

#Chemistry,#HomeChemistry,#HomeChemistry15,#Science, #RedCabbageIndicator,#pH,#Scale,#Acid,#Alkali,#Neutral,#Color,#Scale

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Home Chemistry 14

New chemistry order arrived on Wednesday, this equipment will allow for further useful chemistry both at home and at the STEM group meeting.

Volumetric flask is used to make accurate measurements when making up specific volumes of liquids or solutions.

A burette can be used for Titration. An solution of known concentration is put in to the burette, an solution of unknown concentration is can be put in the flask. The two can be mixed by adding a very small amount at a time, for example 0.5ml or 1ml.

Links

• Better equipped
• Science Forums
• Molar Solution Calculator

Tags

#Chemistry,#HomeChemistry,#HomeChemistry14,#Science,#Equipment, #MolarSolutionCalculator

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Home Chemistry 13

At the March STEM group meeting last month we undertook an activity using red cabbage indicator.

I have been working on a follow up activity to examine what happens when eggshells are added to vinegar and how this changes the pH of the solution.

Equipment

• Test tube rack
• 2 x Test tubes
• 2x pipettes
• Goggles
• Lab coat (optional)
• Gloves (optional but ideal if you have some)
• COMMON SENSE

Chemicals

• White Vinegar
• Red Cabbage indicator
• Egg shells (crushed to small pieces)

Method

We will use one test tube as a 'control' to compare the results.

1. To the first test tube add 6 ml of Vinegar and 6 ml of Indicator.
2. Repeat for the second test tube.
3. Shake gently to mix if needed
4. To one of the test tubes only add some crushed egg shells, make sure they reach the liquid in the test tube
5. Shake gently if needed to help mix

If you now wait a while you will notice a colour change in the second tube, compared to the first tube.

What is happening

The calcium carbonate (alkali) in the eggshell reacts with the vinegar (acid) and neutralises the acid. You should be able to see bubbles.

Results

The control is on the left hand side, results are on the right. You can see a clear difference in colour.

Further reading

• Chemistry of Egg shells
• Red Cabbage pH indicator

We can have a go at this at the Saturday STEM group meeting to confirm the results and may be try this out with different acids.

Maybe discuss further and share results on the Science Forums – Experiments section

Tags

#Chemistry,#HomeChemistry,#HomeChemistry13,

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Home Chemistry 12

I have made a video where I give a basic introduction to using the Molecular solutions calculator from Physiology Web.

I am just using Citric Acid as an example of how the calculator works.

This is a good tool to double check your calculations.

I have uploaded what I hope is an improved version of this.

Tags

#Chemistry,#HomeChemistry,#HomeChemistry12,#MolarSolutions, #Calculator

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