C6- Chemical Synthesis

The Chemical Industry

The chemical industry converts raw materials (crude oil, natural gas, air, minerals, water) into useful products.
The industry makes bulk chemicals on a scale of 1000's of tonnes (ammonia, NaOH, H2SO4, Cl, ethene).
Fine chemicals are made on a smaller scale (drugs and pesticides).
The part of the chemical works that produces the chemical is the plant.
People with many different skills are needed in the chemical industry (researchers, inventors, financial experts, engineers, transporters).

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Concentrated acids are dangerous, but dilute acids are needed for reactions in cells and harnessing energy from respiration.
Organic acids are molecular, molecules consisting of C, H and O atoms. The acidity arises from the H in the -COOH group.
H2SO4, HCl and HN03 acids come from inorganic or mineral sources.
Alkalis (NaOH, KOH) have a pH of above 7. They neutralize acids and are caustic; attack living tissues.
The pH scale is a number scale that shows the acidity or alkalinity of a solution in water. Indicators change colour to show whether a solution is acidic.
Acids react with metals to produce salt and hydrogen gas.
Acids react with a metal oxide or hydroxide to produce salt and water.
Acids react with carbonates to form a salt, carbon dioxide and water.

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When acids mix with water, they dissolve and react to produce hydrogen ions- ionic theory.
All acids contain H in their formulas; in organic acids, it is only the -COOH groups that ionize.
Strong acids (HCl, H2SO4, HNO3) ionize completely when they dissolve in H2O. Weak acids (organic acids) only ionize slightly.
Alkalis consist of metal ions and hydroxide ions; when they dissolve, they add hydroxide ions to water and make it alkaline.
During a neutralization reaction, the H ions from acid react with hydroxide ions from alkali to make water. The remaining ions make a salt.
Salts are ionic- consist of +ive metal ions (from metal oxide/hydroxide) and -ive non-metal ions (from acid).

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Soluble salts are used in our lives. For use in food and medicine, the salts have to be purified.
Kidneys remove toxic chemicals from blood; in case of kidney failure, dialysis machines do the job of the kidneys.
Inside the machine, the blood goes past a membrane- salts on other side of membrane pass into blood, toxic chemicals pass out of blood.
Calcium chloride is used as a dialysis salt. Too much or too little is harmful, needs to be balanced. The CaCl has to be pure and measured accurately.

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Chemists measure the rate of reaction by finding the quantity of product produced or reactant used in a fixed time.
Average rate= change in the volume of product/ time take to happen.
Most rates of reactions change with time, fast at start but slows down.
Factors affecting rate of reaction-
- The concentration of reactants- higher the conc., the faster the reaction.
- The surface area of solid- smaller the surface area, faster the reaction.
- The temperature- higher the temperature, faster the reaction.
- Catalysts- speed up a chemical reaction.
A catalyst is a chemical that speeds up the reaction without being used in the process.
According to the collision theory, when molecules collide, some bonds between atoms break and some form, creating new molecules.
Any change that increases the number of successful collisions per second has an effect of increasing the rate of reaction.

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Adding up the relative atomic masses for all the atoms in a formula of a compound give the relative formula mass.
Given the relative formula masses, it is possible to work out the reacting masses of the reactants and products.
The actual yield is the mass of a product after it is separated from the mixture, purified and dried.
The theoretical yield is the mass of a product expected if the reaction goes exactly as shown in the balanced equation. The actual yield is always less than the theoretical yield, because of by-products and loss of chemicals when moving from containers.

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Chemical synthesis is a way of making new compounds.
Making a sample of magnesium sulfate to react with an acid-
1. Choosing the reaction- any of the characteristic reactions of acids to make salts.
2. Risk assessment- to look for hazards arising from equipment or procedure.
3. Working out the quantities to use.
4. Carrying out the reaction in suitable apparatus under the right conditions- the reaction is fast enough at a temperature and is safe using the equipment.
5. Separating the product from the reaction mixture.
6. Purifying the product.
7. Measuring the yield and checking the purity of the product.

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