Acid + Carbonate

Carbonate is found in lots of rock-forming minerals as well as in egg shells, corals and oyster shells. It is a major component of limestone, and of marble. 
What happens when carbonate minerals, shells, corals and marble statues meet acids?  
AUS-e-TUTE has just added a new tutorial, game, test and exam to help you write word equations for carbonate and acid chemical reactions. AUS-e-TUTE members should log-in to use these new resources.

A "free-to-view" tutorial is currently available to non-members at

https://www.ausetute.com.au/weacidcarbonate.html

Sodium Bicarbonate

One of the single most useful and versatile chemicals I have in my kitchen pantry is a box of sodium bicarbonate, also known as baking soda or bicarbonate of soda.
Read the March 2018 issue of AUS-e-NEWS to find out what makes this compound so special.

Subscribe for free at http://ausetute.com.au/ausenews.html

Cholera Vaccine

The holiday season is here, and some friends have decided to visit Panama (where else would an Engineer want to go for a holiday but to the Panama Canal?). One of the diseases they want protection against before traveling there is cholera which is caused by a water-born bacteria. The product they are taking is called DUKORAL® which comes in two parts. The first part part is a glass vial containing a whitish fluid which is the oral vaccine made up of inactivated cholera bacteria, which is probably of interest to the biology students reading this. Chemistry students, however, will be much more excited by the second part; a sachet containing a dry granular powder which is labelled as buffer.
The ingredients listed on the buffer sachet are:

• sodium bicarbonate
• citric acid, anhydrous
• raspberry flavour
• sodium carbonate, anhydrous
• sodium citrate
• saccharin sodium

The instructions for use by adults are:

1. Dissolve the effervescent granules from the buffer sachet in a glass of cool water (approximately 150 mL)
2.  Shake the vaccine vial
3. Add the vaccine to the effervescent (bubbly) solution. Mix well and drink mixture.

And, you have to take two of these doses 1 to 6 weeks apart, and 2 weeks before arrival at your destination.
The good news is that most people should be protected cholera for up to two years, so I guess my friends will make their way back to the tropics next year.

Suggested Reading
 http://www.ausetute.com.au/namiform.html
 http://www.ausetute.com.au/wriiform.html
http://www.ausetute.com.au/acidbase.html
 http://www.ausetute.com.au/buffers.html
http://www.ausetute.com.au/esters.html

Suggested Study Questions

1.  What is another, systematic name for sodium bicarbonate?
2. Give the molecular formula for each of the following:
   • sodium bicarbonate
   • citric acid, anhydrous
   • sodium carbonate, anhydrous
   • sodium citrate
3. Draw a structural formula for each of the following:
   • sodium bicarbonate
   • citric acid, anhydrous
   • sodium carbonate, anhydrous
   • sodium citrate
4. Use chemical terms to explain the relationship between:
   • sodium bicarbonate and sodium carbonate
   • citric acid and sodium citrate
5. Explain what a buffer is.
6. Explain why the dry, granular powder in the sachet was labelled "buffer".
7. Why do you think a buffer is needed for this vaccine to be effective?
8. What type of chemical compound is the "raspberry flavour" likely to be?
9. One molecule responsible for raspberry flavour is shown below:
   
   What 2 reactants would you need to produce to this molecule in the school laboratory?
10. What does the term effervescent mean?
11. Write a balanced chemical equation to show why effervescence is observed when the buffer in the sachet is added to water. 
12. What does the term "anhydrous" mean?
13. Why are some of the buffer sachet's ingredients listed as "anhydrous"?
14. What is the purpose of the saccharin in the buffer sachet?

CGS and the Solvay Process

Coal seam gas (CSG) is any naturally occurring gas, such as methane, that is trapped in underground coal seams by water and pressure. Methane, often called natural gas, is a commercially valuable resource, so mining companies drill into the coal seam, pump the water out, which releases the pressure and forces the gases to the surface. Queensland is believed to have about 98% of Australia's coal seam gas reserve. More than 4,000 CSG wells in Queensland account for about 17% of that state's electricity. NSW has about 500 CSG wells.

The water that is produced in coal seam gas mining is not suitable for human consumption. The water is most often very salty and can contain heavy metals and toxic compounds.
A new drilling project in the Pilliga Forest in the north-west of NSW is expected to produce an average of 3 tonnes of salt a day over three years!

(http://www.smh.com.au/environment/coal-seam-gas-industry-faces-salt-overload-20131204-2yqx8.html#ixzz2mYw2aSQc)

That's a lot of salt! Left to itself, lying around near the mine, it will poison land and waterways. So what can you do with all this salt?

Salt, sodium chloride, is an important commercial chemical. It is used to produce chlorine and sodium hydroxide, and is used in other industrial process, it is used directly for snow and ice control, as a mineral in animal diets, as a preservative, as a flavouring agent, and as a reagent for water softening. The total (deliberate) production of sodium chloride world-wide is about 250 million tonnes per year.

One way to get rid of the salt produced in coal seam gas mining is to turn it into something else, sodium carbonate for instance.
In Australia, the Penrice Soda Products company in Osborne, South Australia, operates a plant using the Solvay Process to turn sodium chloride into sodium carbonate.
The overall chemical equation for the Solvay Process is
CaCO₃(s)   +   2NaCl (aq)      Na₂CO₃(aq)   +   CaCl₂(aq)
 CaCO₃(s) is present in limestone and the NaCl is the by-product of the CGS mining.
The company currently produces about 325,000 tonnes of sodium carbonate every year.

Further Reading:
density
yield

Solvay Process

Suggested Study Questions:

1. How much NaCl will the Pilliga Forest mining project produce in one year?
2. Assume that there are 4,500 CSG mines in Australia and they each produce 3 tonnes of salt a day. How much salt will be produced in one year in Australia from CSG mines?
3. The density of sodium chloride is about 2.2 g/cm³. Calculate the volume of salt produced each day by the Pilliga Forest CSG mine.
4. Assume a single truck can carry 100 tonnes of salt. How many truck loads of salt will be produced at the Pilliga Forest CSG mine each year?
5. Give one environmental issue that would be raised in trucking salt over large distances. Explain how the problem could be reduced.
6. Give one commercial problem associated with trucking salt over large distance using the same truck. Explain how the problem could be reduced.
7. What is the maximum amount, in tonnes, of sodium carbonate that could be produced using 1 truck load of sodium chloride?
8. What is the maximum amount, in tonnes, of calcium carbonate required to completely convert 1 tonne of sodium chloride to  sodium carbonate?
9. If the actual yield of sodium carbonate is 86.2%, what mass of sodium carbonate would be produced from the complete reaction of 1 tonne of sodium chloride?
10. Assuming the solvay process was used to convert all the salt from all Australia's CSG mines into sodium carbonate, how much sodium carbonate would be be produced?
11. World production of sodium carbonate is currently about 42 million tonnes per year. If Australia began production of sodium carbonate using all the salt produced in the CSG mines, what percentage increase would there be in world production of sodium carbonate?
12. What would you suggest Australia do with the salt produced as a by-product of coal seam gas mining?