Chemistry Summary Questions

3)Write down the symbol equation for magnesium reacting with oxygen
2Mg+O2=2MgO
12)what does it mean if a liquid is said to be very volatile?
It can evaporate very easily as the intermolecular forces of attraction are weaker
17)what are thermochromic pigments?give four uses for them
they change colour or become transparent when heated or cooled e.g bath toys, baby spoons, drink mugs, mood rings
28)what two conditions are needed for cracking to happen, and why?
An aluminium oxide catalyst and hight temp of 400-700 degrees
33)give two advantages of complete combustion over incomplete combustion
waste products of only carbon dioxide and water that are clean and non-poisonous. it releases lots of energy
34)write down a balanced symbol equation for the incomplete combusion of ethane (C2H6)
C2H6+302=CO+Co2+3H2o

2)Briefly describe the inner structure of the Earth
Crust is Earth's thin outer layer, Lithosphere is the upper part of the mantle and made up of tectonic plate also cold and rigid, Mantle is the solide section and as you go deeper temp increases and becomes less rigid, outer core is liquid, inner core is solid
6)Sketch a labelled diagram showing how a volcano forms
7)How is an eruption of silica-rich rhyolitic lava different from an eruption of iron-rich basaltic lava?
The eruption is explosive and produces thick lava but iron-rich lava's eruption if runny and fairly safe
11)How is glass made?
Melting limestone, sand and soda
12)How is cemenr made? What about concrete?
Limestone and clay are heated to make cement. Sand, aggregate and water are mixed to make concrete.
16)During the pruification process, which electrode gets bigger-Cathode or Anode? Write down the equation for the reaction at the anode and the equation for the reaction at the Cathode
Cathode gets bigger. Cu=Cu2+ +2e- (Anode), Cu2+ +2e-=Cu (Cathode)

17)Give an example of a large-scale use of each of the folliwing: brass, solder, amalgam
Musical instruments, meld things together, Dentristry
18)What two metals is brass made from? How are it's physical properties different from those metals?
Made of copper and zinc. It is much harder
19)Give an example of a smart alloy. What is it used for?
Nitinol frames that can be bent and go back to their original shape
20)Write down the word equation for the corrosion of iron
Iron+oxygen+water=hydrated iron (III) oxide
28)Write a word equation for the reaction between phosphoric acid and potassium hydroxide
Phosphoric acid+ sodium hydroxide=sodium phosphate + water
30)Write a balanced symbol equation for the reaction between nitric acid and ammonia
HNO3 + NH3=NH4NO3
35)Describe how you could produce ammonium nitrate in the lab
Add a few drops of methyl orange indicator to ammonia-yellow. slowly add acid until it's neutralised. To get ammonium nitrate cyrstals gently evaporate and leave to crystallise. To get pure then no indicator.

38)Give 5 factors that affect the cost of producing a chemical on an industrial scale
Price of Energy, Cost of raw materials, labour costs, plant costs, Catalsyts
39)Describe two ways that salt can be mined
Drilled, blasted and dug out using machinery. Also, by pumping hot water underground. the salt dissolves and forced to the surface by water pressure-solution mining.

1a) Give and example of an endothermic reaction.
Thermal decomposition
2)Is bond breaking exothermic or an endothermic reaction
Endothermic
3)Give the formula that you would use to find the amount of energy transferred to the water in a calorimetric experiment
Energy transferred = mass of water * SHC of water * Temp change
9)Why do fine combustible powders sometimes explode?
They have a large surface area
10)A peice of magnesium is added to a dilute solution of hydrochloric acide, and hydrogen gas is produced. the experiment is repeated with a more concentrated hydrochloric acide. how can you tell from the experiment which concentration of acide produces a faster rate of reaction?
When using concentrated acid it will take less time to produce the same amount of gas then when using the dilute acid-rate of reaction is faster. The slope of the graph will be steeper for the concentrated acid
12)Write down the three steps of the method for calculating reacting masses.
     a)what mass of magnesium oxide is produced when 112.1 g of magnesium burns in air?
      -balance equation, relative formula masses, divide to get one, then multiply to get all-40g

15)What is the formula for percentage yield? How does percentage yield differ from actual yield?
(Actual Yield/Predicted Yield)*100
19)It can take 12 years and about £900 million to bring a new drug to market. Explain why.
It costs a lot because it goes through research and development (finding suitable compound), Trialling (animal and humans-has to meet legal requirements), manufacture (labour intensive, energy and raw materials-extracted from plants)
20) In terms of intermolecular bonds, explain why diamond makes a good cutting tool
it has strong covalent and intermolecular bonds which require lots of heat to break so it has a high MP.
23) How might fullerenes be used to deliver drugs to the body?
Fullerenes form a cage around molecules.

1)Describe the famous 'gold foil experiment'. what did Rutherford conclude from it?
Fired +vely charged particles at an extremely thin gold sheet. Most passed straight thorugh and small number deflected backwards. He came up with the theory of nuclear atom. nucleus at centre with cloud of -ve electrons-most empty space
4)What feature of atoms determines the order of the modern periodic table?
Atomic number
12)What is ionic bonding?
Atoms become ions which are strongly attracted to one another. Occurs with non-metlas and metlas to produce giant ionic structures
13)Draw a diagram of a giant ionic lattice and give three features of giant ionic structures.
Ions form a closely packed regular lattice. Ions not free to move so don't conduct electricity. Storng chemical bonds
24)Write word equations and balanced symbol equarions for the reactions between:
   a)Bromine and lithium
25)Give details, with an equation, of a displacement reaction involving the halogens
Chlorine + Potassium iodide=Iodine + potassium chloride

26)Give two properties of metals. explain these properties in terms of the structure of a metal
High melting and boiling points due to strong attraction between delocalised electrons and closely packed positive ions. Also, good conductors of heat and electricity due to sea of delocalised electrons carrying electric current.
28)What is a superconductor? Describe some useful applications of superconductors
A metla that is cold enough that resistance disappears completely. Power cables, strong electromagnets, electronic circuits
29)Name six transition metals, and give uses for two of them
Copper, Iron, Zinc, gold, silver, platinum. Iron-catalyst for haber process, NIckel-hydrogentation of alkenes
30)what are thermal decomposition reactions?
31)What type of reaction between two liquids results in the formation of a solid?
What are these solid products called?
32)Describe a way to test solutions for transition metal ions.
33)Describe three processes used during the purification of surface water
34)A student adds dilute hydrochloric acide and barium chloride to a water sample and a white precipitate is produced. What ions are present in the water?
Sulfate ions

2)How many moles are there in 284g of sodium sulfate?
3)What mass of chlorine is there in 2 moles of magnesium chloride?
4)Give the definition of the relative atomic mass of an element?
It's the avergae mass of an atom of the element compared to the mas of 1/12th of an atom of carbon-12
5)Here's the equation for sodium burning in air to produce sodium oxide: 4Na + O2=2Na2O. Use moles to calculate the mass of sodium that is needed to produce 108.2g of sodium oxide
6)What is an empirical formula? Find the empirical formula of the compound formed when 21.9g of magnesium, 29.3g of sulfuir and 58.3g of oxygen react
7)Calculate the concentration of the solution in g/dm3 formed when 7.5g of calcium hydroxide, is dissolved in: a) 1dm3 of water b)2 dm3 of water
8)How many moles of barium chloride are in 500 cm3 of a o.2 molar solution of barium chloride?
9)How would
10)This nutritional info table was found on an orange juice carton: Angela says that one glass will give her 42% of the guideline daily amount Vit C. Why might she be wrong?
Thw amounts are given per 100g-may eat more or less, you may add other things
11)Why do you need to get several consistent readings in titrations?
To increase the accuracy and to spot any anomalous results

14)
15)Name 3 methods used for measuring the amount of gas produced in a reaction. give their advantages.
Gas Syringe-give volumes to nearest cm3 so accurate, Upturned Measuring Cylinder/Burette-Accurate, Measure the mass of gas-Most accurate
18)
19)What is a reversible reaction?
Forward reaction goes at same rate as backward one.
22)State and explain the conditions used in the contact process
Temp-compromise of 450 degrees (temp should be reduced but slows rate of reaction), Pressure-already on the right, Catalyst-increases the rate of reaction (Vanadium Pentoxide)
23)What is the difference between the strength of an acid and it's concentration?
Strength-what proportion of acid molecules ionise in water, Concentration-measures how many moles of acid.
24)Explain why weak acids react slower than strong acids
It releases few H+ ions so collision frequency is low.
25)What is the ionic equatioin for the reaction between lead nitrate and sodium bromide?

26)How would you test for: a) Sulfate b)Halide
Sulfate-White precipitate of barium sulfate, Halide-Cl is white, Br is cream, I is yellow
27)Describe how you would obtain a dry sample of lead chloride from lead nitrate and calcium chloride.
-Precipitate-Add lead nitrate and fill with distilled water. shake thoroughly so all dissolved. add potassium iodide. Tip both into small beaker and salt should precipitate out
-Filter-put filter paper into filter funnel and stick into conical flask. Pour contents and swill out with distilled water.
-Dry

2)Give a symbol half-equation for the oxidation of Fe2+ to Fe3+
Fe2+-e-=Fe3+
5)Explain how greasing and painting protect against rust
It creates a barrier for the iron and prevents rusting by keeping out water, oxygen or both.
6)Why isn't it always a good plan to buy dented cans of beans
They could be starting to rust
7)An oil drilling platform uses sacrifical protection. What's 'sacrificial protection'?
When you place a more reactive metal with iron
8)Why is hydrogen released during the electroylsis of H2SO4?
It's easier to discharge ions from warer instead of ones from the solute.
9)Write the half-equations at each electrode for the electroylsis of PbI2?
Cathode-Pb2+ + 2e-=Pb, Anode-2I-=I2 + 2e-
10)Describe two ways in which you could increase the amount of product made during electroylsis
Electrolysing for a longer time, Increasing the current
12)Sketch an energy level diagram for the reaction between hydrogen and oxygen

13)Give the definition of a fuel cell
An electrical cell that's supplied with fuel and oxygen and uses energy from the reaction between them to produce electrical energy efficiently
14)Write down the overall reaction in an hydrogen-oxygen fuel cell
Hydrogen + oxygen=water
15)Give two advantages of hydrogen fuel cells over conventional ways of generating electricity
More efficient and the only product is water-no pollution
17)Why is the car industry researching fuel cells?
To replace conventional petrol/diesel engines
18)Why were CFCs initially popular?
They were non-toxic, non-flammable and chemically inert
20)How are free radicals formed?
By breaking covalent bonds
21)Write an equation for the reaction between ozone and chlorine atoms
O3 + Cl*=CLO* + O2

22)One CFC molecule can destory thousands of ozone molecules. Why is this?
CFCs aren't reactive and only break up to form chlorine atoms in stratosphere. So take a long time to be removed as it won't break up in the lower atmosphere and ozone is in the stratosphere
23)Is water hardness caused by calcium sulfate permanent of temporary?
Permanent hardness
24)A sample of water requires a large amount of soap to give a good lather both when it is unboiled and after it is boiled. What types of hardness does it have-none, temporary or permanent?
Permanent
26)What's the optimum temp range for fermentation?
25 degrees to 50 degrees
27)Compare the sustainabilty of ethene hydration and fermentation of sugars
Sustainability-Fermentation of sugars is a renewable fuel so won't run out. Hydration of ethene is a non-renewable fuel produces from crude oil so will run out
28)Are fats and oils: a)alkanes b)alcohols c)esters?
Esters

29)Write down a word equation for saponfication
Fat + Sodium hydroxide=Soap + glycerol
30)How would you test margarine to see if it's saturated or unsaturated?
Unsaturated decolourises bromine water.
33)Describe hwo solvents remove stains
Weak intermolecular forces between solvent molecules. when solvent applied, intermolecular forces form between solvent and greese so surrounded by solvent. When solvent removed, grease removed