160k views
3 votes
314.5g HBr (MMHBr = 80.91g/mol), is mixed into 4.50L solution. Find Molarity (M) of the

solution.

User Jodaka
by
6.7k points

1 Answer

0 votes

Answer:


\boxed {\boxed {\sf M \approx0.864 \ M \ HBr}}

Step-by-step explanation:

The molarity of a solution is the moles per liter. It is found using this formula:


M=\frac { moles \ of \ solute}{liters \ of \ solution}

First we must calculate moles, since we are given grams. To convert from grams to moles, the molar mass is used. This is also given to us, it is 80.91 grams per mole. We can use it as a ratio.


\frac {80.91 \ g \ HBr}{1 \ mol \ HBr}

Multiply by the given number of grams.


314.5 \ g \ HBr *\frac {80.91 \ g \ HBr}{1 \ mol \ HBr}

Flip the fraction so the grams of HBr cancel.


314.5 \ g \ HBr *\frac {1 \ mol \ HBr}{80.91 \ g \ HBr}


\frac {314.5 \ mol \ HBr}{80.91 }=3.88703497714 \ mol \ HBr

Now we know the moles, and can calculate the molarity.

There are 3.88703497714 moles of solute and 4.50 Liters of solution.


M= \frac {3.88703497714 \ mol }{ 4.50 \ L}


M= 0.863785550476 \ mol/ L

The original measurements have 4 and 3 significant figures, so we use the lowest number of 3 for our answer. For the number we calculated, that is the thousandth place.

The 7 in the ten thousandth place tells us to round the 3 to a 4.


M \approx 0.864 \ mol/ L


M \approx 0.864 \ M \ HBr

The molarity of the solution is about 0.864 M HBr.

User Abdelsalam Shahlol
by
6.7k points