SC17/18/19: Periodic Table, Rates of Reaction & Heat Changes Flashcards
SC17b Group 1
Describe where the following are found ( periodic table )
A) Alkali Metals
B) Halogens
C) Noble Gases
A) Alkali Metals - Group 1
B) Halogens - Group 7
C) Noble Gases - Group 0
SC17a Group 1
Describe the properties of Alkali metals
A) Alkali metals have similar physical properties to other metals, being malleable and capable of conducting electricity. Specific group properties include;
- Low melting points
- Soft and easily cut
- Very reactive & ready to form compounds with non-metals
SC17a Group 1
A) Describe the reactions of lithium, sodium and potassium with water.
B) State the pattern that can be found for these reactions
A1) Lithium + Water -> Bubbles fiercly on the surface
A2) Sodium + Water -> Melts into a ball and fizzes about the surface
A3) Potassium + Water -> Bursts into flames and flies about the surface
B) The reactivity of alkali metals increase as you go down the group.
- This is because as we go down group 1, the atoms get larger as an electron shell is added in each period
- The force of attraction between the positive nucleus and the negative outer electrons decreases.
- Making it easier for larger atoms to lose their shells.
SC17b Group 7
1. Describe the colour & physical states of; A) Chlorine B) Bromine and C) Iodine at room temperature
2. Describe the pattern in the physical properties of the Halogens
1A) Chlorine -> Green gas
1B) Bromine -> Brown Liquid
1C) Iodine -> Purple/black solid
2. As you go down the Group 7, their; melting points, Boiling points & density all increase.
SC17b Group 7
Describe the chemical test for chlorine.
- Damp litmus paper is bleached white when it is placed in chlorine. If damp blue litmus paper is used, the paper turns red then white.
SC17b Group 7
Describe the reactions of Halogens with Metals
1. Halogen and metals react to form a metal halide, also known as ionic compounds called salts, containing Halide (X-) ions.
2. Some reactions with iron wool include;
- Flourine + Iron wool -> Cold iron wool burns to produce white iron(III) fluoride
- Chlorine + Iron Wool -> Hot iron wool burns vigorously to produce a bright flame & orange-brown iron(III) chloride
- Bromine + Iron wool -> Hot iron wool burns quickly to produce a dull flame, red-brown iron(III) bromide
- Iodine + Iron wool -> Hot iron wool reacts slowly in iodine vapour to produce grey iron(II) iodide ( Changes colour )
SC17b Group 7
Describe the reactions of Halogens with Hydrogen
1. Halogens react with Hydrogen to form hydrogen halides, which dissolve in water to form acidic solutions.
- These hydrogen halides are gases at room temperatures.
2. Reactions;
- Flourine + Hydrogen -> Explodes in the cold and dark, forming hydrogen fluoride
- Chlorine + Hydrogen -> Explodes with a flame or in sunlight, forming hydrogen chloride
- Bromine + Hydrogen -> Vigorous reaction with burning hydrogen, forming hydrogen bromide
- Iodine + Hydrogen -> Very slow reaction when heated strongly, forming some hydrogen iodide
SC17b Group 7
Explain how the reactivity of halogens can be observed.
1. Displacement Reactions - In a displacement reactions, the more reactive element takes the place of the less reactive one in a compound.
- So, a more reactive halogen displaces displaces a less reactive halogen from a halide compound
2. Electronic Configuration - In group 7, halogens gain 1 electron when they react. Down the groups, the distance between the positive nucleus and the outermost shell with electrons gets further apart.
- This means the force of attraction between the positive nucleus and the incoming negative electron isn’t as strong, so ions do not form as easily and reactivity decreases.
SC17d Group 0
A) Describe the properties of noble gases
B) Describe the pattern in their physical properties
A) Properties include;
- They are colourless
- They have very low melting and boiling points
- They are poor conductors of heat and electricity
B) As you go down group 0, the melting and boiling point both increase alongside the density.
SC17d Group 0
Describe the uses of;
A) Krypton
B) Argon
C) Helium
D) Neon
A) Krypton is used in photography lighting. It produces a brilliant white light when electricity is passed through it.
B) Argon is denser than air. It is added to the space above the wine in wine barrels to prevent oxygen in the air reacting with wine.
C) Helium has a very low density and is non-flammable, so it is used in weather balloons and airships.
D) Neon produces a distinctive red-orange light when electricity is passed through it. This property makes it usefull for making long-lasting illuminated signs.
SC17d Group 0
Explain why noble gases are chemically inert
( In terms of electronic configuration )
1. All noble gases have a complete outer shell, however reactions only take place to become more stable while noble gases are already fully stable.
- Making noble gases unreactive
SC18b Core Practical - Investigating reaction rates
Describe the practical to investigate the reaction between hydrocholoric acid & marble chips
Task - Monitoring the progress of the reaction by measuring the volume of Carbon Dioxide produced
Method;
1. Set up the following apparatus; conical flask, trough, water, delivery tube, measuring cylinder and a clamp
2. Measure 40cm^3 of dilute hydrocholric acid into a concical flask.
3. Add 5g of small marble chips the flask
4. Immediately stopper the flask and start the stop clock
5. Note the total volume of gas produced after every 30 seconds until the reaction has finished.
6. Repeat the experiement using 5g of larger marble chips
SC18b Core Practical - Investigating reaction rates
Describe the practical to investigate the reaction between hydrocholoric acid & sodium thiosulfate
Task - Investigate the effect of temperature on the rate of reaction between sodium thiosulfate & hydrochloric acid.
1. Place 50cm^3 of sodium thiosulfate solution into a 300cm^3 conical flask.
2. Measure out 5cm^3 of dilute hydrochloric acid in a test tube.
3. Clamp the conical flask in place in a water bath at a certian temperature. Place the test tube in a rack in the same water bath.
- Record this temperature.
4. After 5 minutes, remove the flask and place it on a piece of white paper marked with a cross.
5. Add the acid to the thiosulfate and start the stop clock.
6. Looking down from above, stop the clock when the cross disappears.
- Note this time and take the final temperature of the mixture.
SC18b Factors affecting reaction rates
Describe what is ment by Activation energy
A) This is the minimum amount of energy needed for a reaction to occur when 2 particles collide
SC18b Factors affecting reaction rates
Explain how;
A) Concentration
B) Pressure
C) Temperature
D) Surface Area
affect the rate of a reaction
A) There are more reacting particles in the same volume of space, increasing the frequency of collisions which will increase the rate of reaction.
B) Similar to concentration, the reactant particles are squeezed closer together, increasing the frequency of collisions which increase the rate of reaction.
C) The reactant particles will have more kinetic energy, meaning more particles with meet the activation energy needed for a successfull collision, increasing the frequency of successfull collisions.
D) There is more surface for collisions to occur on, increasing the frequency of collisions.
SC18c Catalysts and activation energy
Describe what is ment by a Catalyst and how do they speed up a reaction
- Catalysts are substances that speed up chemical reactions without being permantly changed themselves and without altering the products of the reaction.
- Catalysts provide an alternative reaction route, which requires less activation energy.
- The Catalyst does not alter the overall energy change. However, since less energy is needed to start the reaction, more reactant molecules have enough energy to successfully collide, increasing the rate of reaction
SC18c Catalysts and activation energy
Describe what an Enzyme is and their use case.
- Enzymes are large complex protein molecules that act as catalysts in biological reactions.
- Alcoholic drinks are produced using an enzyme in yeast. This enzyme catalyses the reaction in which glucose is converted into ethanol ( alcohol ) and carbon dioxide.
SC19a Exothermic and endothermic reactions
Define & Explain the following;
A) Exothermic Reactions
B) Endothermic Reactions
A) This is a reaction where energy is transferred from stores of energy in chemical bonds to surroundings.
- This results in the surroundings gaining thermal energy, heating up.
B) This is a reaction where energy is transferred from the surroundings to stores of energy in chemical bonds
- This results in the surroundings losing thermal energy, cooling down.
SC19a Exothermic and endothermic reactions
Describe the energy changes that occur in;
A) Precipation reactions
B) Neutralisation reactions
C) Displacement reactions
D) Salts dissolving in water
A) Precipation reactions can be exothermic or endothermic, depending on the substances involved.
B) Neutralisation reactions are always exothermic.
C) Displacement reactions are also always exothermic.
D) When a salt dissolves in water, the change is exothermic or endothermic, depending on the salt.
- The temperature increases as calcium chloride dissolves
- The temperature deceases as ammonium chloride dissolves.
