chemistry revision form 5=form 5 topics
Post on 18-Oct-2014
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basic concepts on chemistryTRANSCRIPT
Chemistry Revision Form 5 on topics:consumer, rate of reaction, carbon
compound and thermo chemistry
STRUCTURE OF SOAP PARTICLE
•the organic part •the ionic part
•the hydrophobic part
•the hydrophilic part
• the head part•the tail part
d)Compare and contrast the cleansing action of soap and detergents
Property Soap Detergent 1 sources Made from
………………
or ………………
Made from petroleum fractions
animal
plant
Property
Soap Detergent
2 Molecular
structure
R – COO – Na +
Where R is
……………
R SO3 – or
Alkyl group
Property
Soap Detergent
3 Effectiveness in
hard water
Forms
…………………with hard
water
Does not
form scum with hard water
SCUM
Property
Soap Detergent
4 Effectiveness
in acidic water
Forms
……………. with acidic
water
Does not
form precipit
ate with
acidic water
INSOLUBLE FATTY ACID
Property Soap Detergent
5 Cleaning power
Less powerfu
l…………… powerful
MORE
Property Soap Detergent
6 Effect to the environment
Biodegradable and
do not cause any
……………
Some detergents are non biodegradable and kill aquatic lives
POLLUTION
What does hard water contains?
•Hard water contains calcium ion, Ca2+ or magnesium ion, Mg2+.
Food additivesDYES PRESERVATIVES
FLAVOURING AGENTS
ANTI OXIDANTS
STABILIZERS AND THICKENING
TYPES OF FOOD ADDITIVES AND EXAMPLES
EXAMPLES TYPE1) AZO COMPOUNDS
2) SODIUM NITRITE, SODIUM BENZOATE
DYES
PRESERVATIVES
EXAMPLES TYPE3) MONO SODIUM GLUTAMATE (MSG)4) ASCORBIC ACID(VITAMIN C)
5) ACACIA GUM
FLAVOURING AGENTS
ANTIOXIDANTS
STABILIZERS & THICKENING AGENTS
TRADITIONAL MEDICINES
Modern medicine
1. ANALGESICS
2. ANTIBIOTICS
3. PSYCHOTHERAPEUTIC MEDICINES
Relieves pain without affecting onsciousness
Kill or inhibit growth of infectious bacteria
Control symptoms of mental illness
Modern medicine
1. ANALGESICS
2. ANTIBIOTICS
3. PSYCHOTHERAPEUTIC MEDICINES
Aspirin, codeine paracetamol
penicillin
Stimulant ANTIDEPRESSANTANTIPSYCHOTIC –
REVISION QUESTIONS
SAPONIFICATION
ESTER
TO PRECIPITATE SOAP PRODUCED
POTASSIUM HYDROXIDE
Water that contains Ca2+ or Mg2+
Soap react with Ca2+ or Mg2+ to form scumDetergent does not form scum in hard water.
Inhibit growth of microorganisms
Antioxidants
burning sensations in the back, neck, chest; paralysis; numbness in the same areas; tingling or warmth in the face, arms or back; nausea; facial tightness; rapid heartbeat; chest pains, asthma attacks; drowsiness or cravings for other foods.
-Factors that influence rate of reaction
•Size of substance or its Total surface area•Temperature of reactant solution•Concentration of the reactant solution•catalyst
-collision theory •Before a reaction happens particles must first collide•This is to overcome bonds between particles and to form new bonds•But simple collision does not break bonds•Only effective collision or collision with CORRECT ORIENTATIONS and enough energy to overcome activation energy is able to form products
Activation energy • Is the minimum energy needed for the
colliding particles to form new products• The energy needed is also to overcome
bonds between particles and to form new bonds
• For every reaction , the activation energy is fixed
• Only catalyst can provide alternative path which has a lower activation energy
a) Graph 9 shows the results of Experiment I and Experiment II to investigate the factor of catalyst in the reaction of zinc and hydrochloric acid.
Volume of hydrogen gas (cm3)
Time(s)
Experiment II
Experiment I
(i) Which experiment used catalyst? State the name of the catalyst used. [ 2 marks]
• Experiment I
• Catalyst used :
Copper(II) sulphate solution
• (ii) The reaction between zinc and hydrochloric acid releases energy. Draw an energy profile diagram for both reactions in Experiment I and Experiment II.
• Label Ea for the activation energy without a catalyst andE’a for the activation energy with a catalyst.
•
[4marks]
(iii) Explain the difference in the rate of reaction between Exp I and Exp II based on the collision theory. [4marks] • Rate of reaction Experiment I is higher
than experiment II.• The presence of catalyst in exp 1 will
provide an alternative path with lower activation energy• More colliding particles are able to
overcome the lower activation energy• Frequency of effective collision increase
and so rate of reaction also increase
• (a) Diagram 10 show the energy level of Reaction I and Reaction II.
• Based on Diagram 10, compare the energy level diagram between Reaction I and Reaction II.
•
Energy
N2 (g)+ 2O2(g)
2NO2 (g)
H = +66 kJ mol-1
Energy
KCl + AgNO3
AgCl + KNO3
Reaction IReaction II
• Reaction I is an endothermic reaction while reaction II is an exothermic reaction.• In reaction 1, Heat energy is absorbedIn reaction II, heat energy is released
• In reaction I, energy of reactants is lower than the energy of products while In reaction II, energy of reactants is higher than the energy of products
b) Table 10 shows the molecular formula and the heat of combustion for propanol and butanol.
AlcoholMolecular
FormulaHeat of combustion/ kJ mol-1
Propanol C3H7OH -2100
Butanol C4H9 OH -2877
Based on the information in Table 10, compare the heat of combustion betweenpropanol and butanol. Explain why there is a difference in the values of the heat of combustion between propanol and butanol.
[3 marks]
• Heat of combustion for butanol is higher than in propanol.• Because the number of carbon atom
and hydrogen atoms per molecule in butanol is higher than in propanol.• So, more heat energy is released to
form carbon dioxide and water in butanol than heat released in propanol
5) Carbon compound
Diagram shows the structural formula of two organic compounds
K and L.
Compound K Compound L
Compound K and L belong to two different homologous series.
(a) Write the general formula for the homologous series of compound K.
CnH2n+1COOH(b) Name compound L.
methyl propanoate
(c) Compare two physical properties of compounds K and L by completing the following table:
Physical property
Compound K Compound L
odour
Solubility soluble in water
Sharp smell Sweet and Fruity smell
Not soluble inwater
6) Thermo chemistry example of paper 3
Plan a laboratory experiment to investigate the relationship between the molar mass of alcohols on the heat of combustion of alcohols. Your planning should include the following:
(a) Statement of problems
Does an alcohol with a higher molar mass have a higher heat of combustion of alcohols?
What is the relationship between the molar mass of alcohols and the heat of combustion of alcohols?
(b) All the variablesManipulated :variable
Responding :VariableConstant :Variables
Different types of Alcohols
Heat of combustion
volume of water, copper can
(c) Statement of hypothesis
The higher the molar mass of alcohol, The higher the heat of combustion of alcohol
(d) List of substances and apparatus
Substances :Methanol, ethanol, propan-1-ol, and butan-1-ol, water
Apparatus :Copper can, measuring cylinder, Thermometer, spirit lamp, Bunsen burner,Tripod stand, wooden block, Wind shield, electronic balance
(e) Procedure of the experiment1. Measure 100cm3 of water using a measuring cylinder. Pour it into a
copper can2. Place the copper can on a tripod stand3. After 3 minutes, measure and record
the initial temperature of water4. Pour 50cm3 of methanol into a spirit
lamp and weigh it5. Place the lamp on wooden block under
the copper can
6.Light up the wick of the lamp immediately
7.Stir the water continuously using a thermometer while observing the increase in temperature
8.Once the temperature has increased to 30oC, put out the flame immediately
9.Record the highest temperature of water
10.Weigh the spirit lamp with methanol again
11.Repeat step 1-10 by using ethanol, propan-1-ol, and butan-1-ol to
replace methanol
(f) Tabulation of dataType of Alcohols Metha
nolEthanol
Initial temp of water (oC)
Highest temp of water(oC)Mass of spirit lamp before combustion(g)Mass of spirit lamp after combustion (g)
(f) Tabulation of dataType of Alcohols propa
nolbutanol
Initial temp of water (oC)
Highest temp of water(oC)Mass of spirit lamp before combustion(g)Mass of spirit lamp after combustion (g)