PH of 0.015 M HCL is?

2 Answers

I get #1.82#.

Explanation:

#"pH"# is given by the equation,

#"pH"=-log[H^+]#

  • #[H^+]# is the hydrogen ion concentration in terms of molarity.

Since hydrochloric acid is a strong acid, it dissociates into single #H^+# ions in an aqueous solution, which eventually become #H_3O^+# ions due to the presence of water #(H_2O)#, and the #"pH"# will simply be:

#"pH"=-log(0.015)#

#~~1.82#

Apr 6, 2018

See below.

Explanation:

#HCl# is a strong acid. That means that it dissociates completely into #H^+# and #Cl^-#:

#"HCl"_((aq)) -> "H"^+ + "Cl"^-#

This means that the initial concentration of #HCl# is equal to the equilibrium concentration of #H^+#.

Therefore, #["HCl"]=["H"^+]#, and #["H"^+]=0.015" M"# at equilibrium.

Here is an equation that you will need to be familiar with in order to solve this problem:

#pH=-log["H"^+]#

Now, we take our concentration of #["H"^+]=0.015" M"# and plug it in as the equilibrium concentration of #["H"^+]# at equilibrium in the equation, and solve for the #pH#. Here is the setup to obtain the final answer:

#pH=-log[0.015]#

Plug this into your calculator, and the answer will be #color(red)(1.82#, with significant figures (note that the digit #1# in the answer does not count as a significant figure. If you need help with significant figures and pH, please leave a comment.)

I hope that helps!