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Acid Base and Salt Question and Answers

We have learnt that an acid is any compound which yields hydrogen ions (H+) in its aqueous solution. In place of hydrogen ion, it’s batter to write hydronium ions which form due to reaction of H+ with water. For example the reaction of hydrochloric acid (HCl) in water can be written as given below;

HCl + H2 H3O+ + Cl-

At the same time bases are the substance which produces hydroxide ion (OH-) in water. This concept is given by Arrhenius and known as Arrhenius theory. Both of these compounds; acids and bases react with one another to yield two products. One is water, and another is an ionic compound which is known as salt. Such reactions are called as called a neutralization reaction. For example the reaction of sodium hydroxide with hydrochloric acid can be written as given below;

Na+ OH+ H+Cl- → H2O + Na+Cl

Neutralization reactions are always exothermic in nature means they liberate heat which is called as heat of neutralisation.  The amount of it is fixed for any acid and base that is 57.7 kJ per mole of H+.  For any acid and base combination the net reaction is  

H+ (aq) + OH- (aq)  H2O

Since the salts are ionic in nature therefore can exist in the form of ions just as before the reaction.  One of the most common salt, NaCl or basically the table salt which is formed when sodium hydroxide (base) combines with  hydrochloric acid. Other examples include epsom salts (MgSO4) used in bath salts, ammonium nitrate (NH4NO3) used as fertiliser, and baking soda (NaHCO3) used in cooking. We can observe many neutralization reactions in our daily lives. Remember when you have stomach burns that are because of hydrochloric acid. When the hydrochloric acid touches the inner layers of our stomach, we get a burning sensation. We can take a medicine called antacid which is a chemical that has aluminium hydroxide or magnesium hydroxide.  These alkalis can easily neutralize the excess acid in our stomach. Similarly acidic bee stings can be neutralized by calamine lotion, which is a mild base based of zinc oxide. Sulphate and nitrate salts of ammonium are considered to be important agro-chemical fertilisers used for good yield in cultivation. They are formed due to neutralization reaction of ammonia gas and sulphuric acid or nitric acid. The harmful acidic sulphur dioxide gas evolved as this gaseous product from the power generating units could be absorbed by basic calcium hydroxide solution to form harmless calcium sulphate. Let’s do some questions o acid, base and salts. The chemical formula of salts provides the idea about the constituent acids and bases. The cationic part of salt comes from base with the anionic part comes from acid. For example; NaCl is composed of Na+ and Cl- ion. Therefore Na+ must come from base that can be NaOH and Cl- from acid so it can be HCl. So now can you predict the acid and base which forms ammonium nitrate (NH4NO3). It must be NH4OH (base) and HNO3 (acid). 

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Question:1) How can you tell if a substance is an acid, base, or salt? 2) How can you tell if a substance is strong weak or non - electrolyte? 3) How do you write the net ionic equation?

Answers:1-Acid: If it has hydrogen in it. Base: If it has OH in it Salt: If it was the result of a neutralization reaction between a acid and base. You get the salt and water. 2-Well that has many rules...but, all soluble ionic substances are strong. HCl,HI, HBR, H2SO4, NHO3 are all strong. OH with any group 1 elements or Ca,Sr, Ba are strong bases. 3-An example: MnS(s)+HCl(aq)---->MnCl2(aq)+H2S(g) First: Balance equation MnS(s)+2HCl(aq)---->MnCl2(aq)+H2S(g) Second: Dissociate all the strong, soluble compounds. The compounds that are not strong and soluble, just lave them alone. MnS(s)+2H+(aq)+2Cl-(aq)---->Mn+2(aq)+2Cl-(aq)+H2S(g) Third: Omit spectator ions (ions that had no change at all) MnS(s)+2H+(aq)---->Mn+2(aq)+H2S(g)

Question:i had a question on a quiz it said to choose if it is acidic, silightly acidic, neutral, slightly basic or basic. one of them just said Gastric acid or juice, i forgot, has pH 7.25 so what is it? and what is the cation and anion on dihydrogen phosphate? and can someone explain whats the buffer system? thanks! damn i hope i put it as slightly basic :D but why is it slightly basic? and does determining a cation and anion differentiate when you lowry-bronsted theory? like would HPO4^-3 be the anion if its the lowry- bronsted theory?

Answers:Are you sure you got the number right for gastric juice? If your teacher really wrote 7.25 on the quiz, then the answer is slightly basic, because anything with a pH greater than 7 is basic. Since 7.25 is just a little bit greater than 7, I would call this slightly basic. However, in reality gastric juice is very acidic with a pH around 2, and it is referred to as both gastric juice and gastric acid. As for why it is basic or acidic, this is based on the definition of these terms. Any solution with a pH greater than 7 is by definition basic, and any solution with a pH less than 7 is by definition acidic. So if your teacher gives you the pH, you just need to determine if it is greater or less than 7, and do not need to know anything else about the solution. Phosphoric acid, H3PO4, has three acidic OH groups, and each one is capable of losing a hydrogen. If you're just talking about dihydrogen phoshpate, then hydrogen is the cation and dihydrogen phoshpate is the anion. A buffer system allows you to maintain the solution at a roughly constant pH even while adding acidic or basic molecules to solution. If you add a few drops of hydrochloric acid to a beaker of pure water, or to a beaker containing an non-buffered aqueous solution, there will be a dramatic change in pH and the solution will become more acidic (how much it changes depends on the exact amount of water and hydrochloric acid you are using). However, if you have a buffer that can act as a base at pH of your solution, it will bind to the hydrogen ions released by hydrochloric acid, there will be no increase in the concentration of "free hydrogen ions" (which are actually hydronium ions, H3O+). If you add too much of an acid or a base, you will overwhelm the buffer and eventually you will be able to change the pH of the solution. Each buffer works over a specific range of pH values. Phosphoric acid/phosphates are excellent buffers because of the three acidic groups. Each hydrogen can bond to or dissociate from its oxygen over a specific range of pH values, but the range is different for each of the three acidic groups. Buffer systems with only one acidic group are effective over a much narrower pH range. To determine which buffer system is appropriate for a given experiment, you need to know the Ka (acid dissociation constant) or pKa for each acidic group in the molecule. Phosphoric acid has three Ka's, one for each of its three acidic groups. When determining which is the cation and which is the anion, it does not make a difference whether or not you are using Arrhenius acid-base theory or Br nsted-Lowry acid-base theory, except some Br nsted-Lowry reactions do not involve ionic reactants or products. The Wikipedia aritcle on acids has a brief description of the three major acid-base theories, and while it does not answer your question directly, the section on Br nsted-Lowry theory gives an example of reactions that do not involve ions, and the entire section discusses how all of the different definitions of an acid (or a base) relate to each other: http://en.wikipedia.org/wiki/Acid#Technical_definitions .

Question:i got these questions wrong on my most recent test...but i really just, dont know how to get the right answer...could somebody just help to tell me why i was wrong..?? thankss!! (all numbers in answers should be subscript) 13. Which of the following is not a good conductor of electricity? KOH(aq) HNO3(aq) KC2H3O2(aq) C2H5OH --i put down c, the answer was d...how can u tell if all are aq 25. As the pH of a solution is changed from 3 to 6, the consentration of hydronium ions: increases by a factor of 3 increases by a factor of 1000 decreases by a factor of 3 decreases by a factor of 1000 --i put b, the answer was 4...i just confused hydronium and hyddroxide ions didnt i? also, could somebody explain hydronium and hydroxide ions to me, i got like, all of those questions wrong...!! whoch one qoes with OH- and H+?? thanks so MUCHHHH!!!!!!!

Answers:13) when the compounds dissolve (or break apart) in water, you will get ions (in a) K+, b) H+, c) K+) but in d, there are none. C2H5OH wont really break down into any metals. Metals are good conductors of electricity (and so are acids, hence the H+) 25) i assume you know the factor (3 to 4 = 10, 3 to 5 = 100, 3 to 6 = 1000....just keep adding 0's or multiply by 10). Hydronium is H+ and hydroxide is OH- (oxide = oxygen) If the pH goes from 3 to 6, it's becoming less acidic, 1 is most acidic and 14 is least acidic (better known as most basic). If it's becoming less acidic (AKA more basic), then there is a decrease of H+ (AKA increase in OH-), or in more chem terms a decrease in hydronium ions and an increase in hydroxide ions hope it helped