Chemistry help?!?
Q1)How could you show gold, silver and platinum don't react with dilute acids?
Q2)What might happen if you tried to show the reaction of sodium with dilute hydrochloric acid in a laboratory?
Thank you in advance!!
Answer:
Combine them and see no reaction (no bubbles, no dissolving of the metal).
If you try this with sodium, dilute acid will react violently.
Q1.i don't get it much!@ Sorry, my English is bad haha!
But if you want to show gold, silver, platinum doesn't react with dilute acids, you just...pour them in! No gas forms, no color changes...no reaction.
Q2, you don't want to put Sodium (Na) in to dilute acids cuz dilutes acids have a lot of water! And you know Na is very reactive metal, it will "booooom" if it directly react with water!
I hope i'm not wrong hehe!
Q1) Get some dilute acid and put equal amounts in two different test tubes. Measure the pH of both (should be the same). Add one of the metals to one of the tubes. Wait for a bit - 10 mins? Measure the pH of both tubes again.
If the pH has not changed then it's likely the metal hasn't reacted with the acid and changed it's pH.
The second tube is your "control". There shouldn't be any changes in this tube either, but if there are that would suggest there has been a problem and you'd need to check your experiment.
1) Note that it is true that gold silver and platinum will completely dissolve in strong acids or aqua regia as long as the mole to mole ratio is equivalent. (Basically add enough of each for the reaction to go to completion) These three metals do react with dilute acids. Dont forget dilute acids are simply strong acids that have been diluted. If you add these metals to dilute acids, remember there is still acid present. However the concentration is so small that you can hardly observe it reacting.
2) If you add sodium to dilute acid it will react. Sodium reacts violently with water and dilute acids are mostly water. When added the sodium will flare up, and hydrogen gas will be generated. Also when you react sodium with water one of the products besides hydrogen is sodium hydroxide(aq). You will also have an acid base reaction taking place.
There are a limited number of indications for a chemical reaction:
1. Temperature change
2. Bubbles
3. Change of state, without deliberately changing temperature.
4. Change of colour
5. Production of energy - heat and/or light.
Q1 If none of the above happen then there is unlikely to be a reaction. (Note not all reactions have an observable change)
Q2 The reaction between sodium and any acid is extremely violent. There is likely to be an explosion as the hydrogen gas will be ignited by the heat produced by the reaction, possibly showering the lab with hot sodium!
1. Weigh the metal. Place it in the acid. Allow to stand for 30 minutes. Take the metal out. Dry it off (take care you dont get acid on yourself). Weigh the metal. If there has been no change in the weight then you can conclude that the metal did not react with the acid. If there has been a change in the weight then you can conclude that some of the metal must have dissolved in the acid and therefore it reacted with the acid.
2. The sodium will react vigorously with the acid and, in all likelihood, will whizz around on the surface of the liquid producing hydrogen. The heat of the reaction is enough to set the hydrogen alight. The products of the reaction will be sodium chloride and hydrogen. The sodium will also react with the water in the acid to produce sodium hyroxide but this will immediately react with the hydrochloric acid to produce sodium chloride (again) and water. Be careful if you carry out this experiment. The reaction can be violently explosive and I have seen the burning metal fly out of the reaction apparatus into a crowd of watching students.
Put a sample of the metal in a dilute solution of hydrochloric,if no bubbles after one minute wash it off then try same with dilute sulphuric acid wash: the same with dilute nitric.Try each metal through the same tests.Obey lab safety rules,acid in eyes is very dangerous and painful,acid on clothes makes holes in them.
Q2)sodium in cold water is quite fizzy.sodium in dilute acid would react so fast it might boil and spray out of the flask.It would give off hydrogen and heat up fast enough so the hydrogen in the flask could explode as it burns in the air in the flask.WEAR ARMOUR IF YOU EVER TRY THIS.
For year 9 simply with dilute acids no bubbles are formed, therefore no reaction.
Sodium reacts violently with water, magnesium very slowly, but with dilute acid magnesium reacts very quickly, so sodium would be much more violent, hence at your level only very small pieces of sodium are use to show this.
1) Add a few drops of the dilute acids to each metal in turn, there will be no effervescence (bubbling), so no hydrogen formed so no reaction.
2) When sodium reacts with water it displaces the hydrogen in the water giving off the hydrogen (the water is acting here like a VERY dilute acid (HOH).
2HOH + 2Na >>>>>>>> 2NaOH + H2.
This gives off a lot of energy, just think what would happen with an acid like HCl... BOOM!
2HCl + 2Na >>>>>>2NaCl + H2 + sacked teacher.
q2 u would leave the lab very quickly
react the metal with an acid in a testube and there wont be any bubbles
i wouldn't react cause chlorine gas is released
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