When Acids React With Alkalis Biology Essay

In this probe, I shall be look intoing how much energy is transferred as heat when acid reacts with bases and whether concentration affects the sum of energy being transferred.

Scientific background information:

Acids are substances with a PH of less than 7. The stronger the acid, the lower the PH figure. Acids dissolve in H2O to organize H+ ions. Alkalis are substances with PH of higher than 7. The stronger the base the higher the PH figure. Alkalis dissolve in H2O to organize OH- ions. Substances with PH graduated table of 7 are impersonal. [ 1 ]

Acid and alkalis react to organize impersonal merchandises such as H2O. Acid responding with an alkali causes its PH to fall because the base is removed by its reaction with the acid. A reaction in which sourness or alkalinity removed is called a neutralization reaction. A neutralization reaction which involves acid and base produce a salt and H2O. The equation is as follows:

Acid + alkali i? salt + H2O [ 2 ]

When there is a chemical reaction, energy is normally transferred to or from the milieus. There are two types of reactions:

Endothermic reactions – Endothermic reactions are reaction that takes in energy from the milieus, normally in signifier of heat. This can be noticed by autumn in temperature of the surrounding. Example of exothermal reaction is photosynthesis. Endothermic reactions are non really common.

Exothermic reactions – Exothermic reactions are reactions that give out energy, normally in the signifier of a heat. This can be noticed in alteration of temperature. Example of exothermal reaction is firing fuels.

energy_transfer1 [ 3 ]

When there is a chemical reaction, chemical bonds are either broken or either formed. Endothermic reaction is a type of reaction where merchandises have more energy than the reactants, therefore it is interrupting bonds. Energy form the milieus is used to interrupt the bonds. Breakage of bonds in chemical reaction releases energy. Exothermic reaction is a type of reaction where merchandises have less energy than the reactants. It is reaction where bonds are made. [ 4 ]

Hypothesis:

Apparatus:

Thermometer- Thermometer is needed to mensurate the temperature of the reaction. Measuring the temperature allows us to cipher the energy alteration of the reaction. Temperature besides allows us to state whether a reaction is endothermal or exothermal.

Copper cup holder – Polythene cup holder as used in the experiment to back up the polyethylene cup to cut down hazard of spillages.

Polythene cup ( 8 ) – Polyethylene cups are used in the experiment to transport out the experiment. Polythene cups are used instead than prove tubings because they are insulator ; they do non carry on heat, no heat is lost to the surrounding, which will intend that the consequences are more accurate. The usage of different paper cups to transport out the experiment will besides restrict the demand for repeated lavation which will salvage clip and will besides do certain that no neutralized solution is left in the cup.

Measuring cylinder- Measuring cylinders are used in the experiment to mensurate the appropriate sum of acid/alkali needed. The mensurating cylinder used is marked in ‘ml ‘ to do the measurings precise. Separate mensurating cylinders should besides be used in order to do my experiment a just trial. Using the same measurement cylinder to mensurate the sum of acid and base will ensue in neutralization taking topographic point in the cylinder instead than the paper cup.

Acid – Acid will be used to transport out a reaction with Alkali.

Alkali- Alkali will be used to transport out a reaction with Acid.

Stopwatch- Stopwatch will be used in the experiment to do certain that we measure the temperature for each trial at a peculiar clip ; this will do consequence in my informations being dependable

Health and Safety:

Health and safety safeguards must be taken while transporting out this experiment.

Wear goggles- It is of import to have on goggles to protect our eyes from any spills that could go on. If you are working with higher concentration of acids or base, full screen goggles must be used. Acids and bases used in the experiment are caustic and irritant.

Carry out the experiment standing- It is of import to transport out the experiment standing, so that there is less opportunity of hurt go oning to you. If something happens, i.e. acids spills, you can rapidly travel from the country.

Positioning of equipment- Acids and Alkalis should be kept in a place where they are non likely to fall or slop. It should n’t be kept at border of the tabular array. Equipment such as mensurating cylinder which is made out of glass could fall and interrupt easy if placed unsuitably, i.e. border of the tabular array. Broken pieces of spectacless are hazard, it could easy cut person.

Skin contact- Acid is unsafe and classed as thorn. If there is contact with tegument ; wash instantly with plentifulness of H2O. Acid spilled on tegument can do tegument irritated, if annoyance persists, seek medical attending.

It is besides recommended to have on latex baseball mitts as they are thin, see through and will non make trouble for you while making the experiment. Latex baseball mitts will make a barrier between the substances and your manus. Wearing baseball mitts protects our manus organize the annoyance which could be caused by acid.

Wearing goggles and latex baseball mitts will intend that there is maximal skin protection and minimises opportunities of annoyance and roseolas from substances coming in contact with the tegument. Handss should besides be washed after making the experiment.

Factors:

Independent variables:

The independent variables in the experiment are:

Dependent Variables:

The dependent variables in the experiment are

Controlled variables:

The controlled variables in the experiment are:

Temperature- Temperature decidedly affects an exothermal or an endothermal reaction. The experiment should be carried out in room temperature. Furthermore, the temperature in which the acid and base are kept at should stay changeless, i.e. if an acid that has a higher temperature is being used during the experiment, the rise in temperature will besides be higher.

Type of acid- Different type of acid have different belongingss and can do different temperatures.

Type of alkali- Similarly, different type of bases have different belongingss, if this does non stay changeless in my experiment, it could do the consequence obtained biased.

Sum of acid- It is necessary to utilize the same sum of acid throughout the experiment,

Sum of alkali-

Concentration of alkali-

Preliminary trial:

In order to see if there were any alterations necessary to be made in the existent experiment, I conducted a preliminary experiment.

Method:

Collect all the setup needed as indicated in the apparatus list above.

Fix the concentrations needed for the experiment. Concentration is worked out by:

Concentration of acerb = Mol. ( coveted molar concentration ) * ( Ml needed )

Original molar concentration

*The expression above merely gives the sum of acid needed for a peculiar concentration. Therefore distilled H2O should be added to do up the sum that is needed.

Measure the temperature of the acid and the base

Pour base onto the cup, follow by adding acid. Let the reaction to happen and mensurate the temperature of the reaction.

*The alteration in temperature is worked out by subtracting the temperature of the acid before the reaction and temperature during the reaction.

5. Repeat each trial three times for dependability.

6. Repeat stairss 4-5 for all the concentration of acid that will be used in the experiment.

I am look intoing whether a concentration of acerb affects neutralization. The sulfuric acid in the experiment will be diluted to do the concentration weaker. I will utilize 2.0 grinder of sulfuric acid and thin this finally down to 0.25 grinder. The sum of acid that will be used throughout the experiment is 20 cm3.

Here is how I diluted the concentration.

Molar of H2S04

Volume of sulfuric acid ( cm3 )

Volume of H2O ( cm3 )

0.25

2.5

17.5

0.50

5

15

0.75

7.5

12.5

1.0

10

10

1.25

12.5

7.5

1.50

15

5

1.75

17.5

2.5

2.0

20

0

Consequences table:

Temperature when assorted with alkali / ( temperature alteration ) [ & A ; deg ; C ]

Mol. of acid

Get downing temperature of acid and base ( & A ; deg ; C )

Trial 1

Trial 2

Trial 3

Average

0.25

20

21.5 /

25

25

24

0.5

20

24

29

31

28

0.75

20

22

35

34

30.33333

1.0

20

28

32

32

30.66667

1.25

20

31

31.5

31

31.16667

1.50

20

30

30

32

30.66667

1.75

20

30

30

29

29.66667

2.0

20

29

29

30

29.33333

Real trial

Temperature when assorted with alkali / ( temperature alteration ) [ & A ; deg ; C ]

Mol. of acid

Get downing temperature of acid and base ( & A ; deg ; C )

Trial 1

Trial 2

Trial 3

Average

0.25

20

22

24

25

0.5

20

24

26

25

0.75

20

25

24

25

1.0

20

26

25

24

1.25

20

25

25

25

1.50

20

26

26

26

1.75

20

26

27

27

2.0

20

26

28

27

In order to get a direct reading of the temperature during the reaction, I would utilize a digital thermometer. Digital thermo metre besides gives consequence in one decimal topographic point which in bend makes my consequence precise. The thermometer used in the experiment- quicksilver thermometers could besides be unsafe if it breaks. Mercury thermometers have scale in them which means that there could human mistakes while reading the temperature. There could besides be parallax mistake while reading the information from the thermometer.

However, utilizing digital thermometer could besides ensue in systematic mistake and the consequence might non be dependable.

I would besides utilize mensurating cylinders which have a higher truth, to mensurate the sum of acid and base. This enables me to hold a precise sum of base and acid needed.