Chem-151 Prelab 7: Standardization Chemistry Department Queensborough Community

Question

Chem-151 Prelab 7: Standardization Chemistry Department Queensborough Community College DUE: 4 April 2017 we perform only Parts A and B of this experiment. Objectiwe 1. (1 pt) State the Objective of this experiment. Introduetion 2. (1 pt) Calculate the normality of the following solutions. (a) 1.5 M KOH (b) 0.3 M H,SO (c) 0.35 M Ba(OH) (105MH,PO Materials and Methods 3. (1 pt) Weighing paper typically weighs between 1 and 2 grams per piece. How many sigmificant digits do you reoord for the weight of the paper (see Part B, Step 2)? t. (1 pt) What is the role of phenolphthalein in this experiment? Data and Results 5. (1 pt) If the buret of NaOH read 0.55 ml initially and 9.37 ml at completion, what volume of NaOH was used? 6. (1 Bowus pt) What is the principle Result of this experiment? Give proper units Discussion 7. (1 Boxus pt) What is a possible source of systematic eror in this experiment? Conclusions 8. (1 Bowus po) Carbon dioxide reacts with water. What is the name of the product of this reaction (see Part A, Step 1)?

Explanation / Answer

1) Objective of the experiment is to determine the molarity and normality of acid and base.

2) Molarity of an acid and base can be converted to Normality by multiplying Molarity by the number of hydrogen ions in the acid and hydroxide ions in base.

a) 1.5 M KOH

Number of hydroxide ions ion in KOH =1

N = (M)( hydroxide ions)

N = 1.5 x 1 = 1.5 N

b) 0.3MH2SO4

Number of hydrogen ion = 2

N = (M)( number of hydrogen ions)

N = 0.3 x 2 = 0.6 N

c) 0.35 M Ba (OH)2

Number of hydroxide ions ion in Ba (OH)2 = 2

N = (M)( hydroxide ions)

N = 0.35 x 2 = 0.70 N

d) 1.05M H3PO4

Number of hydrogen ion = 3

N = (M)( number of hydrogen ions)

N = 1.05 x 3 = 3.15 N

3) Weight of weighing paper should be recorded up to 3 significant figures.

4) Phenolphthalein is used as indicator.

5) Final Volume of NaOH = final burette reading – initial burette reading = 9.37 ml – 0.55 ml = 8.82 ml

8) CO2 reacts with water forming carbonic acid.

H2O + CO2 = H2CO3(aq)

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