October 11, 2019 - WordPress.com · 10/11/2019 · October 11, 2019 Acids, Bases & Indicators...
Transcript of October 11, 2019 - WordPress.com · 10/11/2019 · October 11, 2019 Acids, Bases & Indicators...
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Warm Up
i) Write the balanced chemical equations for the following reactions
ii) Identify the kind of substance of each chemical: element, ionic compound, molecular compound
iii) Identify the kind of particles each substance is made of: atoms, ions or compounds
magnesium + oxygen ‐‐> magnesium oxide
sodium + aluminum chloride ‐‐> aluminum + sodium chloride
methane + oxygen ‐‐> carbon dioxide + waterNOTE: Methane is CH4
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Exploring a Single Displacement Reaction
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Match each of the following using the word bank on the whiteboard. 1. One reactant reacts to form two or more products2. A + BC ‐‐> B + AC3. sugar reacts with oxygen to form carbon dioxide and water4. 3 NaCl + AlF3 ‐‐‐> AlCl3 + 3 NaF5. magnesium + oxygen ‐‐‐> magnesium oxide6. A + B ‐‐‐> AB7. When two compounds react to form two new compounds8. potassium chlorate ‐‐‐> potassium chloride + oxygen9. AB + CD ‐‐‐> CB + AD10. An element reacts with a compound to form a new element and a new compound11. N2 + 3 H2 ‐‐‐> 2 NH3
12. When anything reacts with oxygen13. 2 NaHCO3 ‐‐‐‐> Na2CO3 + CO2 + H2O14. When two or more reactants combine to form just one product15. 2 Li + H2O ‐‐‐> H2 + 2 LiOH
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For each of the following eight reactions:
i) identify the reaction type ii) write the word equation above itiii) identify the type of each substance iv) identify the particle type of each substance
v) balance the chemical equation.
Note: SO4‐2 is called sulfate
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Acids, Bases & Indicators
Acids
Acids are compounds, that when dissolved, release protons (H+) into solution. The will have the formula HA, where H is the proton or protons, and A is a negative ion. A common acid is found in our stomach and it's known as hydrochloric acid. Its formula is HCl.
Even though acids are molecular, the hydrogen acts like a metallic ion because it's lost its electron and so it's just a proton floating around. When it finds somewhere to go, energy gets released and that's why acids are corrosive and can chemically burn us.
Bases
Bases or alkalines are substances that are the opposite of acids. They are corrosive too but instead of releasing protons, they accept them. Most bases are easy to spot because they have the hydroxide (OH‐) which will accept the proton and become water. These kinds of bases have the formula BOH, where B is a metallic ion. A common base, found in drano, is called sodium hydroxide. Its formula is NaOH.
Indicators
Indicators are substances that change colour depending on how acidic or basic a substance is. We used an indicator called phenolphthalein to indicate the presence of hydroxides when we reacted lithium with water to form hydrogen and lithium hydroxide. When the hydroxides formed they turned the phenolphthalein indicator bright pink. Litmus will turn red in the presence of acids and blue in the presence of bases. pH paper will actually indicate how acidic or basic a substance is through various colours. A pH of 7 is neutral, neither acid nor base, and it turns pH paper light green.