One liter of approximetely 0.25N HNO3 has been prepared. Upon titration it was found that 5.0 ml of the acid required 11.0 ml of 0.10N NaOH for neutrality. How much concetrated HNO3 at 15.8N must be added to one liter to make it exactly 0.25N?
HNO3+NaOH=NaNO3+H2O
No. of moles of NaOH = 0.011*0.1 = 0.0011M
Therefore no. of moles of HNO3 in 5ml.
= 0.0011M
Concentration of diluted HNO3
= 0.0011/0.005=0.22N
Volume of 15.8N HNO3 required = x litre.
0.22N*1 litre+15.8x = 0.25(1+x)
Solve for x to get
x=3/1555
=0.00193 l.
=1.93 ml.
To find out how much concentrated HNO3 needs to be added to one liter to make it exactly 0.25N, we can use the concept of normality, which is a measure of the concentration of an acid or base in a solution.
Let's break down the steps to solve this problem:
1. Determine the number of equivalents of NaOH required for neutrality:
- Given that 5.0 ml of the acid (HNO3) required 11.0 ml of 0.10N NaOH, we can calculate the number of equivalents of NaOH used.
- Equivalents = Normality (N) * Volume (in liters)
- The number of equivalents of NaOH used = 0.10N * (11.0 ml / 1000 ml) (convert ml to liters)
2. Calculate the number of equivalents of HNO3 present in 5.0 ml of the acid sample:
- Since we know that HNO3 reacts with NaOH in a 1:1 ratio, the number of equivalents of HNO3 is equal to the number of equivalents of NaOH used.
3. Calculate the normality of the acid sample:
- Normality of the acid = Number of equivalents of HNO3 / Volume of the acid sample (in liters)
- In this case, the volume of the acid sample is given as 5.0 ml. Convert it to liters by dividing by 1000.
4. Find the volume of concentrated HNO3 needed to make the solution 0.25N:
- Concentration of the concentrated HNO3 = 15.8N
- Volume of concentrated HNO3 needed = (0.25N * 1 liter) / (concentration of concentrated HNO3 in N)
Putting it all together:
Step 1: Calculate the number of equivalents of NaOH used:
Number of equivalents of NaOH used = 0.10N * (11.0 ml / 1000 ml)
Step 2: Calculate the number of equivalents of HNO3 present in 5.0 ml of the acid sample:
Number of equivalents of HNO3 = Number of equivalents of NaOH used
Step 3: Calculate the normality of the acid sample:
Normality of the acid = Number of equivalents of HNO3 / (5.0 ml / 1000 ml)
Step 4: Find the volume of concentrated HNO3 needed to make the solution 0.25N:
Volume of concentrated HNO3 needed = (0.25N * 1 liter) / 15.8N
By following these steps, you should be able to determine the volume of concentrated HNO3 needed to make the solution exactly 0.25N.