Topic 2: Chemical Changes Flashcards
In a school laboratory what piece of equipment is used to heat a substance?
Bunsen Burner
Name the FIVE different sections of a Bunsen burner.
Barrel, regulating collar, air hole, gas tubing and the base.
What SIX safety precautions should you take when using a Bunsen?
Tie long hair back, roll up sleeves/take off blazer, tuck in your tie, put on safety goggles, remove any flammable liquids and don’t leave gas on for too long before lighting.
Number the following statements 1-4 according to the order you must follow when lighting a Bunsen burner:
- Move the collar until the air hole is 1/3 open
- Turn on the gas by moving the gas tap
- Attach the rubber tubing to the gas tap
- Light a wooden splint and hold it above the chimney
- Attach the rubber tubing to the gas tap
- Move the collar until the air hole is 1/3 open
- Turn on the gas by moving the gas tap
- Light a wooden splint and hold it above the chimney
What is the colour of the flame when the air hole is 1/3 open?
Yellow/tinged blue
What is the colour of the flame once the air hole is fully opened?
2 toned blue
What is the colour of the flame when the air hole is completely closed?
Yellow (safety flame)
What are the THREE observations for each type of flame when the air hole is open and when the air hole is closed?
Air hole open: 1. roaring 2. slight blue colour 3. hard to notice
Air hole closed: 1. quiet 2. yellow/orange 3. easy to see
What is the colour of the flame and metal present of sodium chloride when heated?
Flame colour: yellow
Metal present: sodium
What is the colour of the flame and metal present of potassium chloride when heated?
Colour of flame: lilac
Metal present: potassium
What is the colour of the flame and metal present of strontium chloride when heated?
Colour of flame: red
Metal present: strontium
What is the flame colour and metal present when calcium chloride is heated?
Flame colour: brick red ( orange red )
Metal present: calcium
What is the flame colour and metal present of copper chloride when heated?
Flame colour: blue-green
Metal present: copper
What is the flame colour and metal present when barium chloride is heated?
Flame colour: apple green
Metal present: barium
What colour of flame does sodium produce?
Yellow
What is the correct change of state when a solid turns to liquid and then to gas?
The solid melts into a liquid and then the liquid evaporates into a gas
What is the correct change of state when a gas changes into a liquid and then to a solid?
The gas condenses into a liquid and then the liquid freezes into a solid
What are changes called when something is heated that can be changed back on cooling?
Reversible changes
What are changes called on heating that cannot be changed back on cooling?
Irreversible changes
Is ice melting reversible or irreversible?
Reversible
Is the wax on a candle burning reversible or irreversible?
Reversible
Is the wick on a candle burning reversible or irreversible?
Irreversible
Is boiling an egg reversible or irreversible?
Irreversible
Is baking a cake reversible or irreversible?
Irreversible
Is making a clay pot and firing it in a kiln reversible or irreversible?
Irreversible
What are the observations of magnesium ribbon being heated and is it reversible or irreversible?
Observations: bright white light
Irreversible
What are the observations of ice being heated and is it reversible or irreversible?
Observations: melts ( turns into a liquid)
Reversible
What are the observations of candle wax being heated and is it reversible or irreversible?
Observations: Melts
Reversible
What are the observations of copper carbonate being heated and is it reversible or irreversible?
Observations: green powder turns black
Irreversible
What are the observations of a wooden splint being heated and is it reversible or irreversible?
Observations: black ash
Irreversible
What are the observations of bread being heated and is it reversible or irreversible ?
Observations: burns/chars
Irreversible
Does sugar dissolve or melt into tea?
Dissolve
Does ice dissolve or melt into lemonade?
Melts
Does salt dissolve or melt into soup?
Dissolve
Does ice cream dissolve or melt on a sunny day?
Melt
What is the term of a liquid that can dissolve a solid?
Solvent
What is the term of a solid dissolves in a liquid?
Solute
What is the term of something does not dissolve?
Insoluble
What is the term of the liquid formed when a solute is dissolved in a solvent?
Solution
What is the term of a substance which can dissolve?
Soluble
What is the definition of soluble?
A substance which can dissolve
What is the definition of insoluble?
Something which does not dissolve
What is the definition of solute?
A solid that dissolves in a liquid
What is the definition of solvent?
A liquid that can dissolve A solid
What is the definition of solution?
The liquid formed when a solute is dissolved in a solvent
What is the appearance of sugar before mixing with water and the appearance after mixing with water?
Before: white crystals
After: clear, colourless liquid
What is the appearance off flour before mixing with water and the appearance of flour after mixing with water?
Before: white powder
After: white cloudy fog/suspension
What is the appearance of copper sulfate before mixing with water after mixing with water?
Before: blue crystal powder
After: a light blue clear substance
What is the appearance of calbalt chloride before mixing with water and after mixing with water?
Before: a purple wet powder
After: a red/purple clear substance
What is the appearance of sand before mixing with water and after mixing with water?
Before: dry mud/rocky/sandy
After: foggy and clear with mixture at the bottom, cloudy suspension
Does the substance sugar form a solution and is it soluble or insoluble?
Yes
Soluble
Does the substance flour form a solution and is it soluble or insoluble?
No
Insoluble
Does the substance copper sulfate form a solution and is it soluble or insoluble?
Yes
Soluble
Does the substance cobalt chloride form a solution and is it soluble or insoluble?
Yes
Soluble
Does the substance sand form a solution and is it soluble or insoluble?
No
Insoluble
Why is it important to use the same volume of water when testing each substance?
To keep it a fair test
A suspension is a solid that does not dissolve but just mixes with a liquid. Which substances in the experiment formed a suspension?
Flour and sand
Describe what happens to a suspension that has been allowed to sit for some time.
It sinks to the bottom of the test tube
How could you separate the insoluble solid from the water?
Filtration
What happens when you use filtration to separate the insoluble solid from the water?
The sand residue gets caught on filter paper and the clear water passes through
What are the SEVEN pieces of apparatus to carry out a filtration experiment?
Filtered liquid ( filtrate ), filter funnel, filter paper, liquid and insoluble solid, beaker, filtered solid residue, conical flask
How could you retrieve the sugar from the sugar solution?
Heat some on an evaporation basin with a Bunsen burner
Name the apparatus used to retrieve sugar from a sugar solution.
Tripod, wire gauze, Bunsen burner, evaporating basin
Name apparatus used for finding out the maximum amount of copper sulfate that will dissolve in 25 cm³ of water at room temperature.
Wire gauze, measuring cylinder, beakers, spatula, filter paper funnel, evaporating basin, tripod, mass balance, Bunsen burner
What safety precautions do you have to remember whilst using a Bunsen burner?
Wear safety goggles and tie long hair back
Describe the method of finding out the maximum amount of copper sulfate that will dissolve in 25 cm³ of water at room temperature.
- Measure out 25 cm³ of water into a 100 cm³ beaker
- Add one spatula of copper sulfate to the water and stirred, repeat until no more will dissolve
- Weigh an evaporating basin and record mass in a suitable table
- Filter copper sulfate solution and collect filtrate in evaporating basin
- Evaporate of water from solution
- Allow basin to cool and reweigh,record in table
- Use your results to work out how much copper sulfate was dissolved in the 25 cm³ of water.
If your result was 5g and over all you had 25 cm³ work out how many grams of copper sulfate would dissolve in 100 cm³ off water at room temperature.
Answer: 20 cm³
How many grams are the same as 1 cm³?
1g
What is the appearance before and after magnesium burns?
Before: silver metal
After: white ash
What is the appearance before and after paper burns?
Before: white paper
After: dark grey ash
What colour are the ashes when you burn magnesium and paper?
Magnesium: white ash
Paper: dark grey ash
What colour are the flames whenever magnesium and paper burns?
Paper: orange and smokey
Magnesium: bright white light
What other substance is needed for burning to occur other than fuel and heat?
Oxygen
What is the new substance formed called when magnesium burns?
Magnesium oxide
What is the bright light when magnesium burns used for?
Stress flares or fireworks
What are the three essential things in a fire triangle to keep a fire burning?
Fuel,heat and oxygen
If a chip pan catches fire should you
A. Place a damp tea towel over the fire
or
B. Lift the pan and put it on the worktop away from the heat?
A. Place a damp tea towel over the fire
What colour of flame would sodium chloride burn with?
Yellow
What colour of flame would calcium chloride burn with?
Brick red
What colour of flame would strontium chloride burn with?
Red
What colour of flame would potassium chloride burn with?
Lilac
What change is solid - liquid?
Melting
What change is gas - liquid?
Condensing
What change is liquid - gas?
Boiling
What change is liquid - solid?
Freezing
Is ice a liquid,solid or gas?
Solid
Is oxygen a liquid, solid or gas?
Gas
Is petrol a liquid, solid or gas?
Liquid
Give two examples of a reversible change
Candle wax,ice
Give two examples of an irreversible change
Magnesium ribbon, copper carbonate, wooden splint, bread
Name the process that causes the clothes on a line to dry
Evaporation
Name TWO substances that dissolve readily in water.
Sugar, copper sulfate and cobalt chloride
Name TWO substances that do not dissolve in water.
Sand and flour
Give a definition for soluble.
A substance which can dissolve
Give a definition for solute.
A solid that dissolves in a liquid
Give a definition for solvent.
A liquid that can dissolve a solid
Give a definition for solution.
The liquid formed when a solute is dissolved in a solvent
How would you separate an insoluble solid from water?
Filtering/filtration
A mixture of chalk and water is filtered using a filter paper and funnel. The chalk stays in the filter paper because it is what?
Insoluble
What are the units for solubility?
g/100g
Describe what happens when magnesium burns.
Bright white shining flame and it turns into white ash
Three essential things are needed for burning, what are they?
Heat fuel and oxygen