Revision for Acids and Bases
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What is the difference between acids and bases?
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An acid is a substance that donates H+ ions and a base that donates OH- ions
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What is the difference between dilute and concentrated?
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A concentrated solution has many molecules (less water and more acid/base), whereas a dilute solution has less molecules (more water and less acid/base)
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What is the unit of concentration?
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Molar (M)
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What is the pH scale?
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A scale used for measuring the number of hydrogen ions in solution. Runs from 0-7: 7 > acidic 7 - neutral 7 < Basic
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What is the proper term for a base?
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Alkali
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What colour changes occur when Universal Indicator is added to an acid and a base?
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Acid: Red Base: Blue
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What are 3 common household bases?
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Bleach Nail remover Soap Cement Antacids Washing powders (Most) cleaning products
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What happens when acids and bases react?
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Neutralisation occurs, and water and salt are created as by-products.
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What happens when acids and metals react?
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Hydrogen gas and a salt are produced
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What are 2 natural occurances of acidic reactions?
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acid rain and ocean acidification
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How does Molarity relate to concentration? (Eg... 2M compared to 0.5M. Which is more concentrated?)
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The higher the Molarity the more concentrated the solution is.
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List examples ratios explaining the difference between dilute and concentrated.
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Concentrated- 6 parts water to 4 parts cordial Dilute- 6 parts water to 1 parts cordial
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How do you read a pH scale? What sections represent acid, base, and neutral?
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Read according to the colours. Left section (0-6) is acidic, middle section (7) is neutral and the right section (8-14) is basic.
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What is another name for a basic solution?
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Alkali.
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How do liquid pH indicators work?
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Chemicals in the indicators change colour when they are added to the acid or base.
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What is a way to produce more reliable results when measuring pH?
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By conducting multiple trials and/or using different indicators.
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How does acid rain affect structures around the world?
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The slight acidity in rain (caused by pollution in the air) destroys marble structures and other stones/metals/objects.
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What are 3 differences between acids and bases?
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An acid is a substance that releases hydrogen ions into an aqueous solution. A base is a substance that releases hydroxide ions. Acids have a pH of less than 7. Bases have a pH of more than seven. Bases are caustic and acids are corrosive. Acids have a sour taste and bases have a bitter taste.
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What does Molarity (M) refer to?
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Molar (M) refers to the concentration of the acid or base. The higher the Molarity, the higher the concentration.
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What causes natural chemicals to become indicators? (What is the agent in these natural chemicals?)
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Natural chemicals such as cabbage juice all contain a chemical called anthocyanin. Anthocyanin is a pigment/colouring agent that is a complex molecule. It changes its structure and reaction according to the acidity of the environment it is exposed to.
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What are different types of indicators that can be used to determine pH?
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Universal indicator, methyl orange, red cabbage juice, bromothymol blue, phenol red, azolitmin.
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How does Ocean Acidification impact oceans?
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Ocean acidification is also a huge issue, changing the acidity levels that fish are adapted to - therefore causing many fish to die and affecting humanity's supply of fish.
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What happens to a solution when a universal indicator is added to it?
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The solution changes colour and the pH can be determined by comparing the colour of the solution to the pH chart.
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Can red cabbage juice be used to determine the pH of solutions?
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Red cabbage juice CAN be used as a pH indicator. A specific indicator chart is needed.
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What happens if you mix a base with a pH level of 8 with an acid with a pH level of 6?
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Neutralisation occuurs: the solution becomes Neutral- with a pH level of 7.
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I have 2 beakers filled with the same volume of acid. I added 200mL of water to beaker A and 100mL of water to beaker B. Which acid would be more diluted?
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Beaker A would be more diluted, as there would be less acid molecules in the solution compared to beaker B.
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For every number you move DOWN the pH scale the concentration of hydrogen ions increases. By what factor does this number increase?
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The concentration increases by 10 every number you move down the pH scale.
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Most pH indicators are made from natural substances, name two fruits or vegetables that can be utilized as a pH indicator.
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Red Cabbage, Blue berries, Carrots, Grapes, etc.
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How do you identify the pH of a substance using a pH scale?
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The concentration of hydrogen ions (H+) in a solution is measured using the pH scale. Using the pH scale, substances matching to the colour of pH 7 are neutral, substances matching to the colour of pH more than 7 are basic and substances matching to the colour of pH less than 7 are acidic.
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What are pH indicators?
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pH indicators are chemicals (often natural) and indicate the concentration of H+ ions in a solution via colour change. With the colour change the substance being tested can be identified as acidic, basic, or neutral .
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List 4 common types of acid/base indicators used to determine pH.
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Methyl orange Universal indicator Litmus paper Phenolphthalein pH meter
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How does ocean acidification affect the environment? Give an example of how it affects an organism.
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Marine organisms that use calcium carbonate for the creation of their shells or skeletons will be in danger because increased acidity will make their shells/skeletons dissolve.
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The more diluted a mixture is, the more water it has in it , the more concentrated a mixture is, the less water it has in it. True or false?
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True.
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The unit of concentration is molar (M). If a mixture is 3M, it would be more concentrated than a mixture of 1M. True of false?
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True
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Name an impact that acid has on the environment and how this impact is caused.
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Ocean Acidification- caused by CO₂ being dumped in the ocean, mixing with water and forming an acid Acid Rain- caused by pollution Global Warming- greenhouse gases forming a hole in the ozone layer
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What are 3 common household acids?
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Lemon juice (any juice) Vinegar Vitamin C Apples Bananas Tea
