Quiz Note: It is recommended that you save your response as you complete each qu

Question

Quiz Note: It is recommended that you save your response as you complete each question. Question 1 (5 points) 10 A student discovers a bottle of NaOH with a partially destroyed pH meter? label. How can the concentration be determined without using a 15 Thes tudent can set-up a titration experiment, where a standardized Ha solution is used to titrate the NaOH The a moles of HT and OH' are equal at the equivalence point, therefore, the concentration of NaOH can be calculated bi The student can set-up a titration expenment, where a standardized NaOH solution is used to titrate HCI. The moles 20 D of Ht and OH are equal at the equivalence point, therefore, the concentration of NaoH can be calculated O o) at the equivalence point should be 7 since this is a neutralization reaction, therefore, the concentration of NaOH is 1 x 10-7 M. Save Question 2 (5 points) What is the hydroxide ion concentration of an unknown acid with a pH of 1.97 0 e) 7.94 x 10-13 M O b) 6.69 x 10-14 M

Explanation / Answer

1) Known volume of NaOH solution is titrated against standard HCl solution of known concentration .At eqvt point moles of H+ is equal to moles of OH-. From the volume of HCl conc. of NaOH can be calculated using the equation

VHCl x NHCl = VNaOH x NNaOH

Option 1

2) pH of the acid = 1.9

we know pH + pOH = 14

pOH = 14 - pH = 14 - 1.9 = 12.1

pOH = - log OH-

ie - pOH = log OH-

log OH- = -12.1

OH- = 10-pOH = 10-12.1 (or OH- = antilog (-12.1)) = 7.94 x 10 -13

OH- Concentration = 7.94 x 10-13

Option 1

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