Monthly Archives: October 2014
|Autumn Leaves-click to enlarge|
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|Earth from Space in colour|
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A pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+). Normally, the indicator causes the colour of the solution to change depending on the pH.
pH (potential of hydrogen) is a scale of acidity from 0 to 14. It tells how acidic or alkaline a substance is. More acidic solutions have lower pH. More alkaline solutions have higher pH. Substances which are not acidic or alkaline (neutral) usually have a pH of 7. Acids have a pH less than 7. Alkalis have a pH greater than 7.
pH indicator solutions are themselves weak acids or bases. As one chemical is added it changes the arrangement of the electrons in the molecule causing it to absorb different wavelengths of light and therefore appear different in colour.
Different chemicals can be used for different pH ranges as shown in the diagram below.
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- Strokes – to reduce the risk
- Pregnancy Complications – Pre-eclampsia and foetal growth retardation, both caused by blockages of the blood vessels of the placenta, are two of the commonest complications of pregnancy – aspirin helps to reduce this risk.
- Colon cancer – In a long term study of 90,000 US nurses between 1976 and 1995, those who took 4-6 tablets of aspirin a week had a reduced incidence of colorectal cancer. The benefits were greatest in those who had taken the drugs the longest.
- Diabetes – Blindness, coronary artery disease, stroke and kidney failure are all common complications of diabetes resulting from impaired blood circulation. The benefits of taking one aspirin a day are now so widely accepted that it is considered unethical to perform placebo controlled trials to prove the case.
- Dementia (including Alzheimer’s disease)- There is some evidence that aspirin may help prevent both the condition resulting from impaired blood flow and the most serious form of dementia, Alzheimer’s disease.
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|Zinc Oxide used in paint pigments|
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