Question 7 (10 points) If an aqueous solution of unknown concentration of HCI ha

Question

Question 7 (10 points) If an aqueous solution of unknown concentration of HCI has a volume of 22.6 mL and takes 19.5 mL of 0.221 M NaOH to be neutralized, what is the molarity of the acid? O 1) 0.191MHCI 2) 191 M HCI O 3) 0.221 M NaOH 4) 0.221 M HC Save Question 8 (10 points) Indicators are used in acid-base titrations because they: O 1) speed up the reaction 2) change color when excess acid or base has been added O 3) always change color in acidic solutions 4) always change color in basic solutions Save MacBook Air

Explanation / Answer

7)
Balanced chemical equation is:
NaOH + HCl ---> NaCl + H2O


Here:
M(NaOH)=0.221 M
V(NaOH)=19.5 mL
V(HCl)=22.6 mL

According to balanced reaction:
1*number of mol of NaOH =1*number of mol of HCl
1*M(NaOH)*V(NaOH) =1*M(HCl)*V(HCl)
1*0.221*19.5 = 1*M(HCl)*22.6
M(HCl) = 0.1907 M

Answer: 0.191 M

8)
Indicator are used to determine the end point of titration
they change color when end point is reached
Answer: 2

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