plug at9 5. What chemical term describes the role of manganese dioxide, Mno, if
ID: 692740 • Letter: P
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plug at9 5. What chemical term describes the role of manganese dioxide, Mno, if your experimental results show that it affects the rate at which the hydrogen peroxide decomposes but the MnO, is completely recovered after the reaction is over. a. Reactant; b. Product, c. Substrate; d d. Catalyst; or e. Oxidizing agent 6. In performing the experiment pH and Neutralization of Acids and Bases, let us say that you used 18.5 drops of saturated calcium hydroxide solution to neutralize 50.0 mL of hydrochloric acid solution. Calculate the drops of saturated calcium hydroxide required per liter of hydrochloric acid. Show all your work below. 7. You performed two neutralization reactions: the reaction of acetic acid, HC,H,O, with saturated calcium hydroxide, Ca(OH), and the reaction of hydrochloric acid with saturated calcium hydroxide. Write a balanced chemical equation for each neutralization reaction. 8. In order to measure how much acid is in a known volume of an acidic sample, we shall measure the minimum volume of a basic solution required to react with all of the acid in the sample. What is this procedure called? a. decantation; b. distillation; c. titration d. extraction If the number of drops of 0.5% acetic acid added to 5 mL of saturated CO,, in order to reach the end point of that indicator, was determined to be 46 drops for bromphenol blue and 10 drops for bromcresol green, which indicator's end point is at the lowest pH? Explain.Explanation / Answer
5) CATALYST
A substance that is used in the reaction but not consumed / recovered at the end of reaction, but affects the rate of reaction is called a Catalyst.
In the decomposition of H2O2 , MnO2 affects the rate of reaction but is recovered after reaction. Thus is tthe catalyst.
6)
50mL of HYdrochloric acid requires 18.5 drops of saturated Ca(OH)2 solution for neutralisation
1000mL of acid solution requires = 1000x 18.5 /50 drops
= 370 drops of Ca(OH)2 solution
7)
acetic acid with calcium hydroxide
2 HC2H3O2(aq) + Ca(OH)2(aq) -------------> Ca(C2H3O2)2 (aq) + 2H2O(l)
hydrochloric acid with calcium hydroxide
2HCl (aq) + Ca(OH)2 (aq) ------------> CaCl2 (aq) + H2O(l)
8) TITRATION
measuring the volumes of acid/ base to calculate its concentration(how much is present) by measuring the volume of known concentration base/acid is called TITRATION.
9) for bromophenol blue 46 drops of acid are used
and for bromocresol 10 drops are used.
As bromophenol blue required more acid to give the end point, it has lowest pH at the end point.
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