2 chemistry viva questions with answers titration
Answers
Question.1.What is a standard solution ?
Answer. A solution whose strength is known is called a standard solution.
Question.2.What is a normal solution ?
Answer. A solution containing one gram-equivalent mass of the solute per litre of the solution is called a normal solution.
Question.3.What is the equivalent mass of KMnO4 when it acts as oxidizing agent in acidic medium ?
Answer. KMnO4 loses 5 electrons per molecule, when it acts as oxidizing agent in the presence of acids. Therefore, its equivalent mass is one-fifth of its molecular mass.
volumetric-analysis-viva-questions-with-answers-1
Question.4.Is sodium hydroxide a primary standard ?
Answer. No.
Question.5.Are ‘molality’ and “molarity’’ same ?
Answer. No, molality of a solution is defined as the number of moles of solute present in 1000 grams of the solution whereas molarity tells us about the number of moles of the solute present per litre of the solution.
Question.6.What would be the normality of 0.10M KMnO4 ?
Answer. It will be 0.1 x 5 = 0.5 N.
Question.7.What volume of 10M HCl must be diluted with water to get 1L of 1M HCl ?
Answer. 0.1L.
Question.8.What is the basicity of H2SO4 ?
Answer. 2.
Question.9.What is the relationship between normality (N), molarity (M), molecular mass and equivalent mass ?
Answer. Normality x Eq. Mass = Molarity x Mol. Mass.
Question.10.Why front door of the balance is closed during weighing ?
Answer. Opening the front door causes vibrations in the pan due to operator’s breath which leads to inaccurate results.
Question.11.What is the maximum weight that can be weighed in a chemical balance ?
Answer.100 grams.
Question.12.What is the weight of a rider ?
Answer. 10 mg.
Question.13.What is the use of a rider ?
Answer. A rider is used for weights less than 10 mg.
Question.14. What is the principle of volumetric analysis?
Answer. In volumetric analysis, the concentration of a solution is determined by allowing a known volume of the solution to react, quantitatively with another solution of known concentration.
Question.15. What is titration ?
Answer. The process of adding one solution from the burette to another in the conical flask in order to complete the chemical reaction involved, is known as titration.
Question.16. What is indicator ?
Answer. Indicator is a chemical substance which changes colour at the end point.
Question.17. What is end point ?
Answer. The stage during titration at which the reaction is just complete is known as the end point of titration.
Question.18. Why a titration flask should not be rinsed ?
Answer. This is because during rinsing-some liquid will remain sticking to the titration flask therefore the pipetted volume taken in the titration flask will increase.
Question.19. What are primary and secondary standard substances?
Answer. A substance is known as primary standard if it is available in high degree of purity, if it is stable and unaffected by air, if it does not gain or lose moisture in air, if it is readily soluble and its solution in water remains as such for long time.
On the other hand, a substance which does not possess the above characteristics is called a secondary standard substance. Primary standards are crystalline oxalic add, anhydrous Na2CO3 , Mohr’s salt, etc.