Acids, Bases and Salts

• Acidic solutions have pH values less than 7.
• What's an acid


  Substance that releases H+ ions when added to water
• How do weak acids react with NA2CO3?

  little effervescence
• How does sulfuric acid react with Methyl orange, Phenolphthalein, Universal Indicator and Litmus?

  Red, colourless, red, red
• How does ethanoic acid react with Methyl orange, Phenolphthalein, Universal Indicator and Litmus?


  Red, colourless, orange, red
• How does ammonia solution react with Methyl orange, Phenolphthalein, Universal Indicator and Litmus?

  Yellow, purple, dark blue, blue
• How does sodium hydroxide react with Methyl orange, Phenolphthalein, Universal Indicator and Litmus?

  Yellow, purple, dark blue, blue
• What are bases?

  Substance that reacts with acids to form a salt and water
• What are alkalis?

  Substance that reacts with water to form OH- ions
• What does BRINCLHOF mean and stand for?

  Form molecules and it stands for Bromine, Iodine, Nitrogen, Chlorine, Hydrogen, Oxygen, Fluorine
• How does HCL and Mg react?

  Effervescence, metal dissapears
• How does HCL and NAOH react?

  Makes colourless solution
• How does H2SO4 react with CUO (black solid)?

  solution turns blue, solid disappears
• How does HCL react with CACO3 (white solid)?

  lots of effervescence, solid disappears
• How do you make a soluble salt?

  Gently warm acid. Add solid till it settles in beaker. Filter away excess solid. Heat solution. Remove 1/3 of water. Leave solution to cool. Filter solution. Dry in a warm oven.
• Why do crystals form when making a soluble salt as the solution cools?

  As the solubility of the solid reduces as the solution cools
• All common Na and K salts are soluble
• All nitrates are soluble
• Most common chlorides are soluble, except silver and lead
• Most common sulphates are soluble, except calcium, lead and barium
• All ammonium salts are soluble
• Most common carbonates/oxides/hydroxides are insoluble, except Na, K, NH4
• What is the chemical test for halides?

  Add nitric acid and silver nitrate, forming a precipitate
• What's the formula for concentration?

  moles/volume(dm^3)
• What's the formula for concentration (g/dm^3)?

  concentration (mol/dm^3) x Mr
• What are titrations used for?

  To measure the concentration of acids and alkalis
• Acids are neutralized when added to a base.
• What is the advantage of using a polystyrene cup rather than a glass beaker?

  It's an insulator so it prevents heat loss
• Why is it better to use phenolphthalein indicator rather than universal indicator in titrations?

  phenolphthalein has only two colours
• Why is a burette used instead of a pipette for adding the acid?

  Pipette measures one volume only
• What colour change would the student see when he neutralises the sodium hydroxide solution?

  pink to colourless
• Describe the method of a titration

  Place alkali into conical flask. Add indicator. Add acid from burette until indicator changes colour. Pour contents of flask away. Evaporate to 1/3 of original volume and leave to crystalise.
• Describe how to make an insoluble solid

  Place acid in beaker and heat. Add base or carbonate or metal until it no longer dissolves. Filter away excess solid. Evaporate and leave to crystalise.
• How do you use precipitation salt prep method

  Add soluble salt of the cation to the soluble salt of the anion. Filter to collect salt. Wash solid with distilled water to remove traces of solution. Dry in warm oven.
• Why would it be better to use a pipette rather than a measuring cylinder?

  More precise
• What extra step should there be between adding each portion of acid and measuring the temperature?

  Stirring
• You can add water to an ionic compound to make them conduct electricity