A50.0ml- volume of 0.15m hbr is titrated with 0.25m koh . calculate the ph after the addition of 13.0ml of koh.

- pH = 1.17

Solution:- HBr is a strong acid and KOH is a strong base. So, it's a strong acid vs strong base titration.

For this type of titration, if we have equal moles of acid and base then solution is neutral and the pH will be 7.

If the moles of base are more than moles of acid then solution will be basic and pH will be more than 7.

And if the moles of acid are more than moles of base then solution will be acidic and the pH will be less than 7.

So, let's calculate the moles of acid and base and see which one is in excess.

HBr and KOH reacts in 1:1 mol ratio which is clear from the below balanced equation:

To calculate the moles we convert mL into L and multiply with the molarity.

= 0.0075 mol HBr

= 0.00325 mol KOH

moles of HBr are more than moles of KOH. So, excess moles of HBr

= 0.0075 - 0.00325

= 0.00425 mol

Total volume of the solution will be the sum of the volumes of acid and base added.

So, total volume = 50.0 mL = 13.0 mL = 63.0 mL = 0.0630 L

Molarity of excess HBr =

= 0.0675 M

HBr is the strong acid so hydrogen ion concentration will be same as the concentration of excess HBr that is 0.0675 M.

So, the pH of the solution = - log(0.0675)

pH = 1.17

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance