Flashcards in Chemistry :( Deck (24)
Define the law of conservation of matter.
Matter can be neither created nor destroyed. The atoms are simply just rearranged to create new substances.
A reaction that absorbs heat, taking it from the surroundings and making it feel colder. The products have more energy than the reactants.
A reaction that releases energy. The reactants have more energy than the products.
Is photosynthesis endo or exothermic?
Is respiration endo or exothermic?
Types of exothermic reactions that require a fuel and an oxygen.
Define complete combustion and provide an example.
A type of combustion that occurs only if sufficient oxygen is present, the products always being carbon dioxide and water. e.g. octane + oxygen gas -> carbon dioxide + water.
Define an incomplete combustion and provide an example.
A type of combustion that occurs when insufficient oxygen is present, the products always being carbon monoxide/water, and carbon. e.g. methane + oxygen gas -> water + carbon
What is the general equation of combustion?
fuel + oxygen gas -> carbon dioxide + water + energy
Define a corrosion reaction.
A type of reaction that requires oxygen and involves metals corroding
substances that release hydrogen ions (H+) into aqueous solutions (e.g. hydrochloric acid in your stomach)
substances that release hydroxide ions (OH+). E.g. ammonia
What are the 6 properties of acids?
- turns blue litmus paper red
- have a sour taste
- conduct electricity
- are neautralised by bases
- react with some metals, releasing hydrogen gas and leaving salt behind.
What are the 6 properties of bases?
- have a soapy, slimy feel
- have a bitter taste
- conduct electricity
- Turn red litmus paper blue
- are neutralised by acids, producing water and salt.
Bases that are soluble in water.
What is the pH scale;
A scale that measures how acidic or basic a substance is, with numbers ranging from 1-14.
Where does an acid fall on the pH scale?
any pH less than 7.
Where does a base fall on the pH scale?
any pH greater than 7
Define a neutral substance.
It is neither acidic nor basic, it contains the same amount of hydrogen and hydroxide ions. It falls on 7 in the pH scale.
What is the general reaction for neutralisation?
acid + base -> salt + water
What is the general reaction for acids and metals?
acid + metal -> salt + hydrogen gas
What is the general reaction for acids and carbonates?
acid + carbonate -> salt + water + carbon dioxide
What is the general reaction for acids and digestion?
hydrochloric acid + sodium hydrogen carbonate -> sodium chloride + water + carbon dioxide