Question

1. which of the following is a weak acid?

a. hydrobromic, hbr
b. hydroiodic, hi
c. hydrofluoric, hf
d. hydrochloric, hcl
e. perchloric, hclo4

1. identify the base in the following acid - base reaction:

$h_{2}o(l)+nh_{3}(aq)\to nh_{4}^{+}(aq)+ho^{-}(aq)$
a. nh3
b. h2o
c. h2o and nh4+
d. oh-
e. nh3 and oh-

1. select the net ionic equation for the reaction of sodium carbonate (na2co3) with hydrobromic acid (hbr).

a. $na_{2}co_{3}(aq)\to 2na^{+}(aq)+co_{3}^{2 - }(aq)$
b. $hbro_{3}(aq)\to h^{+}(aq)+bro_{3}^{-}(aq)$
c. $na^{+}(aq)+br^{-}(aq)\to nabr(aq)$
d. $2na^{+}(aq)+co_{3}^{2 - }(aq)+2h^{+}(aq)+2br^{-}(aq)\to h_{2}o(l)+2na(s)+co_{2}(g)+br_{2}(l)$
e. $2h^{+}(aq)+co_{3}^{2 - }(aq)\to h_{2}o(l)+co_{2}(g)$

1. how many liters of 0.200 m naoh are required to completely neutralize 1.00 l of 0.100 m hcn?

a. 2.00 l
b. 1.50 l
c. 1.00 l
d. 0.500 l
e. 0.250 l

Explanation:

Question 13

Strong acids completely dissociate in water. Hydrobromic acid (HBr), hydroiodic acid (HI), hydrochloric acid (HCl), and perchloric acid ($\ce{HClO4}$) are all strong acids. Hydrofluoric acid (HF) is a weak acid as it does not completely dissociate in water.

In the Brønsted - Lowry theory, a base is a substance that accepts a proton ($\ce{H+}$). In the reaction $\ce{H2O(l) + NH3(aq)\to NH4+(aq) + HO-(aq)}$, $\ce{NH3}$ accepts a proton from $\ce{H2O}$ to form $\ce{NH4+}$.

The reaction between sodium carbonate ($\ce{Na2CO3}$) and hydrobromic acid (HBr) is $\ce{Na2CO3(aq)+2HBr(aq)\to 2NaBr(aq)+H2O(l) + CO2(g)}$. In ionic form: $\ce{2Na+(aq)+CO3^{2 - }(aq)+2H+(aq)+2Br-(aq)\to 2Na+(aq)+2Br-(aq)+H2O(l)+CO2(g)}$. Canceling out the spectator ions ($\ce{Na+}$ and $\ce{Br-}$), the net ionic equation is $\ce{2H+(aq)+CO3^{2 - }(aq)\to H2O(l)+CO2(g)}$.

Answer:

C. hydrofluoric, HF

Question 14