Titrations

Question 1

What is used for any acid base titration

Answer 1

An indicator must be used that will help determine when the titration is at its end point

Question 2

What are indicators

Answer 2

A special chemical that change colour when at a different Ph

Question 3

Give an example of a indicator that can be used in titration

Answer 3

For example phenolphthalein is an indicator that is colourless in a low acidic pH but bright pink on a high alkaline pH

Question 4

What can a titration curve show

Answer 4

The rapid change in the mixture

Question 5

What is the centre of the vertical section of the curve called

Answer 5

Equivalence point of the titration and it is this part that yeh indicator is trying to indicate

Question 6

Why is the choice of an indicator important

Answer 6

It must change colour at a pH that is in the vertical part of the curve otherwise it will miss the equivalent point rending that titration pointless

Question 7

What is the equivalent point

Answer 7

The point in a titration where the volume of k e solution exactly matches the volume of the other solution

Question 8

What does the indicator depend on

Answer 8

On the strengths of the acid and base that are reacting.Different indicators will change colours at different pH. Therefore the pH of the acid and the base must be considered.

Question 9

What are the two factors in conducting a titration curve

Answer 9

The pH

Base

Question 10

What would the indicator phenolphthalein

Answer 10

So it would be suitable for a strong acid/strong base titration but would not above the vertical section of the curve

Question 11

Enthalpy Changes

Answer 11

All chemical reactions can be classified into two distinct types exothermic or endothermic. The category the reaction falls under is determined by enthanlpy change that takes place during the reaction

Question 12

Define Enthalpy

Answer 12

The heat content stored in a chemical system and

Question 13

Describe endothermic reaction

Answer 13

Energy in the form of heat is taken in by the chemical system in order to break the bonds in the reactants, and energy is given out when new bonds from the products.
If more energy is needed to break the bonds than is released when bonds are made then the reaction is endothermic

Question 14

Explain exothermic

Answer 14

If the reverse is the case and more energy is released when bonds are made than taken in when bonds are broken, then the reaction is exothermic

Question 15

What does enthalpy

Answer 15

Heat energy

Question 16

What is an empathy change

Answer 16

It is about energy being given out by a reaction(exothermic) or taken in by a reaction (endothermic)

Question 17

What is the activation energy

Answer 17

Energy needed to start a reaction

Question 18

Define standard enthalpy

Answer 18

The enthalpy change that occurs when one mole of a compound form from its elements under standard conditions

Question 19

Define standard enthalpy change of combustion

Answer 19

The enthalpy change that occurs when one mole of a compound completely combusts oxygen under standard conditions

Question 20

Define enthalpy change of neutralisation

Answer 20

The enthalpy change that occurs when an acid is neutralised by a base forming one mole of water under standard conditions

Question 21

Define enthalpy change of reaction

Answer 21

The enthalpy change that occurs in the molar quantities expressed in the equation understand condition

Question 22

Define standard conditions

Answer 22

25C/298k, 100kPa/1 atm pressure ,1 moldm3 solution concentration

Question 23

Define standard enthalpy change equation

Answer 23

Equation can be written that shows theses different enthalpy change and their specific definition

Question 24

Endothermic reactions

Answer 24

Energy profile shows that the products have more enthalpy than the reactants
heat is taken in from the surroundings so the enthalpy of the system increases
this shows a decrease in temperature
the reaction is not over until the system is back to the same temperature as the surroundings- all the necessary heat energy has been taken in

Question 25

what is an example of endothermic reaction

Answer 25

photosynthesis

Question 26

exothermic reaction

Answer 26

The energy profile shows that the products have less enthalpy than the reactant Heat energy has been transferred from the chemical system to the surroundings as the enthalpy of the system decreases this shows that the temperature decrease the reaction is not over until the system is back to the same temperature as the surroundings- all the heat energy has dissipated into the surrounding-all the heat energy has dissipated into the surroundings

Question 27

what an example of exothermic reactions

Answer 27

combustion | respiration

Question 28

how can we measure enthalpy change

Answer 28

temperature is measured using a thermometer heat is a measure of the total energy of all the particles present in a substance- the number of particles matter a bath of warm water will have more heat than a red hot nail because there are so many more particles in it heat always flows from high to a low temperature

Question 29

Thermochemistry

Answer 29

most chemical reactions involve an energy change: the overall change will result in either : more energy being put in to the reaction to break bonds than is given out (endothermic) more energy being produced by forming bonds that is used to break the bonds(exothermic)