GCSE_Chemistry_Single Archives - Page 2 of 2

3:02 describe simple calorimetry experiments for reactions such as combustion, displacement, dissolving and neutralisation

Calorimetry allows for the measurement of the amount of energy transferred in a chemical reaction to be calculated.

EXPERIMENT1: Displacement, dissolving and neutralisation reactions

Example: magnesium displacing copper from copper(II) sulfate

Method:

50 cm³ of copper(II) sulfate is measured and transferred into a polystyrene cup.
The initial temperature of the copper sulfate solution is measured and recorded.
Magnesium is added and the maximum temperature is measured and recorded.
The temperature rise is then calculated. For example:

Initial temp. of solution (^oC)	Maximium temp. of solution (^oC)	Temperature rise (^oC)
24.2	56.7	32.5

Note: mass of 50 cm³ of solution is 50 g

The cup used is polystyrene because:

polystyrene is an insulator which reduces heats loss

EXPERIMENT2: Combustion reactions

To measure the amount of energy produced when a fuel is burnt, the fuel is burnt and the flame is used to heat up some water in a copper container

Example: ethanol is burnt in a small spirit burner

Method:

The initial mass of the ethanol and spirit burner is measured and recorded.
100cm³ of water is transferred into a copper container and the initial temperature is measured and recorded.
The burner is placed under of copper container and then lit.
The water is stirred constantly with the thermometer until the temperature rises by, say, 30 ^oC
The flame is extinguished and the maximum temperature of the water is measured and recorded.
The burner and the remaining ethanol is reweighed. For example:

Mass of water (g)	Initial temp of water (^oC)	Maximum temp of water (^oC)	Temperature rise (^oC)	Initial mass of spirit burner + ethanol (g)	Final mass of spirit burner + ethanol (g)	Mass of ethanol burnt (g)
100	24.2	54.2	30.0	34.46	33.68	0.78

The amount of energy produced per gram of ethanol burnt can also be calculated:

Hydr0Gen2023-01-10T11:58:51+00:00Categories: (a) Energetics, 3 Physical chemistry, Edexcel iGCSE Chemistry|Tags: 3:02, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Crude oil to plastics (D), Topic: Energetics, Topic: Energetics (D), Topic: Equilibria, Topic: Reversible Reactions (D), Topic: Specification experiments|

3:03 calculate the heat energy change from a measured temperature change using the expression Q = mcΔT

Calorimetry allows for the measurement of the amount of energy transferred in a chemical reaction to be calculated.

EXPERIMENT1: Displacement, dissolving and neutralisation reactions

Example: magnesium displacing copper from copper(II) sulfate

Method:

50 cm³ of copper(II) sulfate is measured and transferred into a polystyrene cup.
The initial temperature of the copper sulfate solution is measured and recorded.
Magnesium is added and the maximum temperature is measured and recorded.
The temperature rise is then calculated. For example:

Initial temp. of solution (^oC)	Maximium temp. of solution (^oC)	Temperature rise (^oC)
24.2	56.7	32.5

Note: mass of 50 cm³ of solution is 50 g

EXPERIMENT2: Combustion reactions

To measure the amount of energy produced when a fuel is burnt, the fuel is burnt and the flame is used to heat up some water in a copper container

Example: ethanol is burnt in a small spirit burner

Method:

The initial mass of the ethanol and spirit burner is measured and recorded.
100cm³ of water is transferred into a copper container and the initial temperature is measured and recorded.
The burner is placed under of copper container and then lit.
The water is stirred constantly with the thermometer until the temperature rises by, say, 30 ^oC
The flame is extinguished and the maximum temperature of the water is measured and recorded.
The burner and the remaining ethanol is reweighed. For example:

Mass of water (g)	Initial temp of water (^oC)	Maximum temp of water (^oC)	Temperature rise (^oC)	Initial mass of spirit burner + ethanol (g)	Final mass of spirit burner + ethanol (g)	Mass of ethanol burnt (g)
100	24.2	54.2	30.0	34.46	33.68	0.78

The amount of energy produced per gram of ethanol burnt can also be calculated:

Hydr0Gen2023-03-06T17:22:19+00:00Categories: (a) Energetics, 3 Physical chemistry, Edexcel iGCSE Chemistry|Tags: 3:03, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Crude oil to plastics (D), Topic: Energetics, Topic: Energetics (D), Topic: Key Calculations|

3:08 practical: investigate temperature changes accompanying some of the following types of change: salts dissolving in water, neutralisation reactions, displacement reactions and combustion reactions

Calorimetry allows for the measurement of the amount of energy transferred in a chemical reaction to be calculated.

EXPERIMENT1: Displacement, dissolving and neutralisation reactions

Example: magnesium displacing copper from copper(II) sulfate

Method:

50 cm³ of copper(II) sulfate is measured and transferred into a polystyrene cup.
The initial temperature of the copper sulfate solution is measured and recorded.
Magnesium is added and the maximum temperature is measured and recorded.
The temperature rise is then calculated. For example:

Initial temp. of solution (^oC)	Maximium temp. of solution (^oC)	Temperature rise (^oC)
24.2	56.7	32.5

Note: mass of 50 cm³ of solution is 50 g

EXPERIMENT2: Combustion reactions

To measure the amount of energy produced when a fuel is burnt, the fuel is burnt and the flame is used to heat up some water in a copper container

Example: ethanol is burnt in a small spirit burner

Method:

The initial mass of the ethanol and spirit burner is measured and recorded.
100cm³ of water is transferred into a copper container and the initial temperature is measured and recorded.
The burner is placed under of copper container and then lit.
The water is stirred constantly with the thermometer until the temperature rises by, say, 30 ^oC
The flame is extinguished and the maximum temperature of the water is measured and recorded.
The burner and the remaining ethanol is reweighed. For example:

Mass of water (g)	Initial temp of water (^oC)	Maximum temp of water (^oC)	Temperature rise (^oC)	Initial mass of spirit burner + ethanol (g)	Final mass of spirit burner + ethanol (g)	Mass of ethanol burnt (g)
100	24.2	54.2	30.0	34.46	33.68	0.78

The amount of energy produced per gram of ethanol burnt can also be calculated:

Hydr0Gen2023-01-10T11:59:24+00:00Categories: (a) Energetics, 3 Physical chemistry, Edexcel iGCSE Chemistry|Tags: 3:08, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Crude oil to plastics (D), Topic: Energetics, Topic: Energetics (D), Topic: Specification experiments|

3:10 describe the effects of changes in surface area of a solid, concentration of a solution, pressure of a gas, temperature and the use of a catalyst on the rate of a reaction

Increasing the surface area of a solid increases the rate of a reaction.

Increasing the concentration of a solution increases the rate of a reaction.

Increasing the pressure of a gas increases the rate of a reaction.

Increasing the temperature increases the rate of a reaction.

Using a catalyst increases the rate of a reaction.

Hydr0Gen2022-11-30T14:30:11+00:00Categories: (b) Rates of reaction, 3 Physical chemistry, Edexcel iGCSE Chemistry|Tags: 3:10, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Kinetics|

3:12 know that a catalyst is a substance that increases the rate of a reaction, but is chemically unchanged at the end of the reaction

A catalyst is a substance that increases the rate of a reaction, but is chemically unchanged at the end of the reaction.

Hydr0Gen2023-01-10T11:20:08+00:00Categories: (b) Rates of reaction, 3 Physical chemistry, Edexcel iGCSE Chemistry|Tags: 3:12, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Equilibria, Topic: Kinetics, Topic: Reversible Reactions (D)|

3:15 practical: investigate the effect of changing the surface area of marble chips and of changing the concentration of hydrochloric acid on the rate of reaction between marble chips and dilute hydrochloric acid

The rate of a chemical reaction can be measured either by how quickly reactants are used up or how quickly the products are formed.

The rate of reaction can be calculated using the following equation:

The units for rate of reaction will usually be grams per min (g/min)

An investigation of the reaction between marble chips and hydrochloric acid:

Marble chips, calcium carbonate (CaCO₃) react with hydrochloric acid (HCl) to produce carbon dioxide gas. Calcium chloride solution is also formed.

Using the apparatus shown the change in mass of carbon dioxide can be measure with time.

As the marble chips react with the acid, carbon dioxide is given off.

The purpose of the cotton wool is to allow carbon dioxide to escape, but to stop any acid from spraying out.

The mass of carbon dioxide lost is measured at intervals, and a graph is plotted:

Experiment to investigate the effects of changes in surface area of solid on the rate of a reaction:

The experiment is repeated using the exact same quantities of everything but using larger chips. For a given quantity, if the chips are larger then the surface area is lesson. So reaction with the larger chips happens more slowly.

Both sets of results are plotted on the same graph.

Experiment to investigate the effects of changes in concentration of solutions on the rate of a reaction:

The experiment is again repeated using the exact same quantities of everything but this time with half the concentration of acid. The marble chips must however be in excess. The reaction with the half the concentration of acid happens slower and produces half the amount of carbon dioxide.

Hydr0Gen2022-11-30T14:30:40+00:00Categories: (b) Rates of reaction, 3 Physical chemistry, Edexcel iGCSE Chemistry|Tags: 3:15, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Kinetics, Topic: Specification experiments|

4:01 know that a hydrocarbon is a compound of hydrogen and carbon only

Hydrocarbon: A molecule containing only hydrogen and carbon

Hydr0Gen2023-01-10T08:33:05+00:00Categories: (a) Introduction, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:01, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers, Topic: Crude oil to plastics (D)|

4:02a understand how to represent organic molecules using molecular formulae, general formulae, structural formulae and displayed formulae

The molecular formula shows the actual number of atoms of each element in a molecule.

The general formula shows the relationship between the number of atoms of one element to another within a molecule. Members of a homologous series share the same general formula. The general formula for alkanes is C_nH_2n+2 and the general formula for alkenes is C_nH_2n.

A structural formula shows how the atoms in a molecule are joined together.

The displayed formula is a full structural formula which shows all the bonds in a molecule as individual lines.

The terms above are demonstrated with the example of butane.

Displayed formula:
Molecular formula: C₄H₁₀
General formula (alkanes): C_nH_2n+2
Structural formula: CH₃ – CH₂ – CH₂ – CH₃

The terms above are demonstrated with the example of ethene, which contains a double bond.

Displayed formula:
Molecular formula: C₂H₄
General formula (alkenes): C_nH_2n
Structural formula: CH₂ = CH₂

Sam Mahal2022-12-12T11:18:38+00:00Categories: (a) Introduction, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:02a, Chemistry, GCSE, GCSE_Chemistry_Single, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers|

4:07 know that crude oil is a mixture of hydrocarbons

Crude Oil is a mixture of hydrocarbons.

Hydr0Gen2023-01-10T08:34:14+00:00Categories: (b) Crude oil, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:07, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers, Topic: Crude oil to plastics (D)|

4:09 know the names and uses of the main fractions obtained from crude oil: refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen

Crude oil is separated into fractions by the process of fractional distillation.

Fraction	Use
Refinery gases	Bottled gas
Gasoline	Fuel for cars
Kerosene	Fuel for aeroplanes
Diesel Oil	Fuel for lorries
Fuel Oil	Fuel for ships
Bitumen	Road Surfacing

Hydr0Gen2023-01-10T08:34:49+00:00Categories: (b) Crude oil, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:09, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers, Topic: Crude oil to plastics (D)|

4:10 know the trend in colour, boiling point and viscosity of the main fractions

The boiling point increases as the number of carbon atoms (chain length) increases.

The viscosity increases as the number of carbon atoms (chain length) increases.

The greater the number of carbon atoms (chain length), the darker in colour that fraction is.

The viscosity of a fluid describes how easily it flows. Water has a low viscosity, it flows very easily. Crude oil has a higher viscosity than water, it does not flow very easily.

Fractions (in order)	Properties
Refinery gases	Smallest molecules. Lowest boiling point. Lowest viscosity. Lightest in colour.
Gasoline
Kerosene
Diesel
Fuel oil
Bitumen	Largest molecules. Highest boiling point. Highest viscosity. Darkest in colour.

Hydr0Gen2023-01-10T08:35:37+00:00Categories: (b) Crude oil, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:10, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers, Topic: Crude oil to plastics (D)|

4:11 know that a fuel is a substance that, when burned, releases heat energy

A fuel is a substance that, when burned, releases heat energy (exothermic reaction).

Hydr0Gen2023-01-10T08:35:44+00:00Categories: (b) Crude oil, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:11, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers, Topic: Crude oil to plastics (D)|

4:12 know the possible products of complete and incomplete combustion of hydrocarbons with oxygen in the air

Complete Combustion happens when there is enough oxygen available, producing carbon dioxide (CO₂) and water (H₂O)

Incomplete Combustion happens when there is not enough oxygen available, with possible products being carbon monoxide (CO), carbon (C, soot), carbon dioxide (CO₂) and water (H₂O)

Hydr0Gen2023-01-10T08:35:55+00:00Categories: (b) Crude oil, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:12, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers, Topic: Crude oil to plastics (D)|

4:13 understand why carbon monoxide is poisonous, in terms of its effect on the capacity of blood to transport oxygen references to haemoglobin are not required

Carbon monoxide may be produced from the incomplete combustion of fuels:

Carbon monoxide is poisonous because it reduces the capacity of the blood to carry oxygen.

Hydr0Gen2023-01-10T08:36:04+00:00Categories: (b) Crude oil, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:13, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers, Topic: Crude oil to plastics (D)|

4:14 know that, in car engines, the temperature reached is high enough to allow nitrogen and oxygen from air to react, forming oxides of nitrogen

When fuels are burned in vehicle engines, high temperatures are reached.

At these high temperatures nitrogen and oxygen from the air react to produce nitrogen oxides:

nitrogen + oxygen → nitrogen oxides

eg

N₂ (g) + O₂ (g) → 2NO (g)

In the atmosphere these nitrogen oxides can combine with water to produce nitric acid (HNO₃).

Hydr0Gen2023-01-10T08:36:12+00:00Categories: (b) Crude oil, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:14, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Condensation Polymers, Topic: Crude oil to plastics (D)|

4:15 explain how the combustion of some impurities in hydrocarbon fuels results in the formation of sulfur dioxide

Fossil fuels such as coal, gas and oil are derived from crude oil.

These fuels are hydrocarbons, but also include impurities such as sulfur.

When the fuels are burned, sulfur dioxide is produced which can escape into the atmosphere:

S (s) + O₂ (g) → SO₂ (g)

Hydr0Gen2023-01-10T08:36:20+00:00Categories: (b) Crude oil, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:15, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Condensation Polymers, Topic: Crude oil to plastics (D)|

4:16 understand how sulfur dioxide and oxides of nitrogen oxides contribute to acid rain

Acids formed in the atmosphere can fall as acid rain. This can be a major problem, killing trees and fish in lakes. The acid rain also corrodes limestone buildings and marble statues since these are both made of calcium carbonate (CaCO₃). Some metals such as iron are also attacked by acid rain.

Sulfur dioxide released into the atmosphere from the burning of fossil fuels can react with water and oxygen to make sulfuric acid (H₂SO₄):

2SO₂ (g) + 2H₂O (l) + O₂ (g) → 2H₂SO₄ (aq)

Also, if sulfur dioxide in the atmosphere reacts with just water, a weaker acid called sulfurous acid (H₂SO₃) is formed:

SO₂ (g) + H₂O (l) → H₂SO₃ (aq)

In car engines the temperature is high enough for the nitrogen in the air to react with oxygen to produce oxides of nitrogen, e.g:

N₂ (g) + O₂ (g) → NO₂ (g)

In the atmosphere these nitrogen oxides can produce nitric acid (HNO₃).

Hydr0Gen2023-01-10T08:36:29+00:00Categories: (b) Crude oil, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:16, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Condensation Polymers, Topic: Crude oil to plastics (D)|

4:19 know the general formula for alkanes

Alkanes have the general formula C_nH_2n+2

This means that to work out the number of hydrogens, you double the number of carbons and then add two.

Hydr0Gen2023-01-10T08:37:06+00:00Categories: (c) Alkanes, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:19, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers, Topic: Crude oil to plastics (D)|

4:20 explain why alkanes are classified as saturated hydrocarbons

Saturated: A molecule containing only single bonds between carbon atoms. For example, alkanes as described as saturated molecules.

Unsaturated: A molecule containing a carbon-carbon double or triple bond. For example, alkenes as described as unsaturated molecules.

Hydr0Gen2023-01-10T11:03:36+00:00Categories: (c) Alkanes, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:20, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers, Topic: Crude oil to plastics (D)|

4:21 understand how to draw the structural and displayed formulae for alkanes with up to five carbon atoms in the molecule, and to name the unbranched-chain isomers

The displayed formulae show all the atoms and bonds drawn out.

The molecular formulae just show the number of each type of atom in the molecule.

Hydr0Gen2023-01-10T11:04:20+00:00Categories: (c) Alkanes, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:21, Chemistry, Double, GCSE, GCSE_Chemistry_Single, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers, Topic: Crude oil to plastics (D)|

4:23 know that alkenes contain the functional group >C=C<

Alkenes are a homologous series of hydrocarbons which contain a carbon-carbon double bond. This double bond is shown in formulae as a double line.

The names of alkenes end with “ene”.

An example is ethene, the structural formula for which is CH₂ = CH₂

For a molecule with more than two carbon atoms, the position of the double bond within the molecule can vary as indicated by the name and the structural formula.