so for my chemistry lab we have to calculate the Molarity of HCl after being standardized with NaOH. the molarity of NaOh was 0.4304M.
10ml of 1M HCl was titrated with the 0.4304M NaOH and reached the equaivalence point at 25.20ml.
how do i find the exact concentration of HCl...i cant figure it out :/
10ml of 1M HCl was titrated with the 0.4304M NaOH and reached the equaivalence point at 25.20ml.
how do i find the exact concentration of HCl...i cant figure it out :/
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Okay, Natalie, it's not that bad. First of all you have to calculate the number of moles of NaOH you used. You know molarity is moles per liter so if you multiply the molarity (moles/liter) times liters, you'll get the number of moles of NaOH you used to neutralize the HCl.
That's just: 0.4304 x 25.20 which = 0.0108 moles.
Now since 0.0108 moles of NaOH neutralized all the HCl you know there were 0.0108 moles of HCl contained in the 10 ml sample. Going back to the same formula: molarity = moles/liters and substituting the exact number of moles and the exact number of liters you used, you can calculate the exact (?) molarity of the HCl.
molarity (HCl) = 0.0108 moles/0.010 liters which = 1.08 molar.
Notice, I placed a question mark after the word "exact". That's because you will never know the exact answer, you can just calculate the answer to the precision of your measurements. Since you are given 10 ml of HCl, you only know the volume of HCl to the hundredths place (0.01 liters) or perhaps to the thousandths place if the last zero is significant which would be 0.010. As a result there's no point in expressing your answer beyond the thousandths place which is why I said the answer is 1.08 or 1.080 molar.
That's just: 0.4304 x 25.20 which = 0.0108 moles.
Now since 0.0108 moles of NaOH neutralized all the HCl you know there were 0.0108 moles of HCl contained in the 10 ml sample. Going back to the same formula: molarity = moles/liters and substituting the exact number of moles and the exact number of liters you used, you can calculate the exact (?) molarity of the HCl.
molarity (HCl) = 0.0108 moles/0.010 liters which = 1.08 molar.
Notice, I placed a question mark after the word "exact". That's because you will never know the exact answer, you can just calculate the answer to the precision of your measurements. Since you are given 10 ml of HCl, you only know the volume of HCl to the hundredths place (0.01 liters) or perhaps to the thousandths place if the last zero is significant which would be 0.010. As a result there's no point in expressing your answer beyond the thousandths place which is why I said the answer is 1.08 or 1.080 molar.