Strong and weak acids and bases

Answer Key - Grade 10 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   HCl and acetic acid are both 0.1 M. HCl ionizes completely, so its [H⁺] is 0.1 M; acetic acid's is 0.0013 M. About how many times more H⁺ does HCl have, Ari?

   77 times
2. 2.

   Acetic acid is 0.4% ionized at 1.0 M and 4.2% at 0.010 M. What does this show, Jun?

   • Its Ka changes with concentration
   • It turns strong when dilute
   • More ionizes when it is dilute
3. 3.

   Which has the lower pH: 0.10 M HCl or 0.10 M acetic acid, Kira?

   • The 0.10 M acetic acid
   • Both have the same pH
   • The 0.10 M HCl
4. 4.

   Why is [H⁺] in 0.10 M HCl equal to 0.10 M, Luz?

   • Every HCl molecule splits
   • Water adds that much H⁺
   • HCl is a concentrated acid
5. 5.

   Milo says acetic acid is weak because vinegar is mostly water. Agree or disagree?

   • Agree: weak just means watered down
   • Disagree: weak means partly split
   • Agree: water makes any acid weak
6. 6.

   Noah says 6 M acetic acid is a strong acid because it is concentrated. Agree or disagree?

   • Agree: concentrated means strong
   • Agree: more acid means it splits more fully
   • Disagree: it is concentrated but weak
7. 7.

   Pia says a strong acid has a lower pH than a weak acid, whatever their concentrations. Agree or disagree?

   • Agree: weak acids have pH above 7
   • Agree: strong acids win at any amount
   • Disagree: concentration matters too
8. 8.

   Citric acid is a weak acid. Why is lemon juice still about pH 2.2, Ren?

   • Lemon juice has HCl in it
   • Citric acid is a strong acid
   • It holds plenty of citric acid
9. 9.

   Milk of magnesia, Mg(OH)₂, is about pH 10.5, far milder than 1.0 M NaOH at 14.0. Why, Tala?

   • Mg(OH)₂ is an acid
   • Little Mg(OH)₂ dissolves
   • It has no OH⁻ in it
10. 10.

    Which pH fits 0.10 M acetic acid, Zee?

    • About 2.9
    • About 7.0
    • About 1.0