4
$\begingroup$

A student has equal volumes of $\pu{1.0 mol dm-3}$ sodium hydroxide and ammonia solutions. Which statement about the solutions is correct?

A. Sodium hydroxide has a lower electrical conductivity than ammonia.
B. Sodium hydroxide has a higher hydrogen ion concentration than ammonia.
C. Sodium hydroxide has a higher pH than ammonia.
D. Sodium hydroxide has a higher hydroxide ion concentration than ammonia.

The answer is C, and I understand why. What I do not understand is why D isn't correct also? Could someone clarify this for me?

$\endgroup$
  • 2
    $\begingroup$ Share some reasoning why C is true and why you think D should be true. $\endgroup$ – bpedit Jan 18 '17 at 4:14
  • $\begingroup$ At first glance I'm inclined to agree with you. Where is this question from? $\endgroup$ – electronpusher Jan 18 '17 at 11:51
  • $\begingroup$ D is also correct but as you know sodium hydroxide is strong base and ammonia solution is a weak base. In weak base solution we must know Kb to calculate hydroxide ion concentration. Although a solution of weak base has lower concentration of hydroxide ion compared to a solution of a strong base having same concentration. $\endgroup$ – narendra kumar Jan 18 '17 at 12:53
1
$\begingroup$

See this website. Essentially it's a misprint in the IB Chem testbank.

https://www.thinkib.net/chemistry/blog/8944/multiple-choice-answers

There's a correct rewording for D that makes C the only correct answer, according to the link I just posted.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.