To investigate how heat is given out in neutralizing sodium hydroxide (NaOH) using different concentrations of Hydrochloric Acid.
Substances that neutralize acids are called alkalis. An acid is a substance that forms hydrogen ions (H+ ) when placed in water. It can also be described as a proton donor as it provides H+ ions. An example of an acid is hydrochloric acid (HCl), Sulphuric acid (H2SO4) etc. An alkali is a soluble base and forms hydroxyl ions (OH-) when placed in water. It can be called a proton acceptor and will accept hydrogen ions to form H2O. An example of an alkali is Sodium Hydroxide (NaOH).
[IMAGE]Acid + Alkali Salt + Water
[IMAGE]Hydrochloric acid + Sodium Hydroxide Sodium
Chloride + Water
[IMAGE]HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
[IMAGE]H+ (aq) + Cl- (aq) + Na+ (aq) + OH- (aq) Na+
(aq) + Cl- (aq) +H+ + OH-
[IMAGE]The above is an example of a neutralization reaction, involving an acid and an alkali. The result is a salt and water. In every neutralization reaction, the metal in the alkali (Na+ here) takes the place oh the hydrogen in the acid, forming a metal compound called a salt. The hydrogen and the hydroxide ions react to form water. As bonds are made this is an exothermic reaction so heat will be given out and this will be shown as an increase in temperature. The chemical energy will be negative ( H is minus).
1. Polystyrene cup
2. Measuring cylinder
3. Thermometer (0. C to 50. C )
4. Test Tubes
5. Sodium Hydroxide
6. Hydrochloric Acid
Hydrochloric Acid molecule
9. Teat Tube stand
I think that the acid of higher concentration will need more alkali to neutralize the acid which also means that there will be a greater change in temperature and there will be more energy released. Linking theory to prediction shows that in a higher concentrated acid there will be more H+ ions so they will have a better chance of coming into contact with the OH- ions and making new bonds which will result in more energy released. For the lower concentration acid less alkali will be needed to neutralize and there will be a low change in temperature and there will be less heat given out. This is because there will be less H+ ions so there will be a lower chance of them coming in contact with the OH- ions, thus there will be less bonds made and less energy given out.
There are risks in this investigation as we are using harmful acids and alkalis used, so we must minimize them. Acids are particularly harmful to the skin and eyes therefore I will be wearing safety goggles and a lab coat. I will also wipe out any spillages. Goggles will be worn to prevent strong acids and alkalis getting in the eyes as they are irritants and may cause permanent damage to the eyes and other parts of body. The thermometer should be handled with care as it has mercury which is poisonous. The apparatus should be handled with care as they might be hot after the reaction. Glass apparatus should be handled with care as they might break if they fall and broken glass might hurt someone. I will be standing while doing the experiment so that if acid or alkali is spilled I move away from it as quickly as possible so that the damage done is minimized. Long Hair will be tied back. Shirt sleeves should be rolled up to the elbow. The lids of the chemicals are closed after they have been used.
For a fair test:-
1. The temperature would be kept the same throughout the experiment because high temperature would decrease the time of reaction resulting in inaccurate results.
2. I would use a fix...
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