Download App

Model Paper 9 — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryModel Paper 95 Marks
Question
A sparingly soluble salt gets precipitated only when the product of the concentration of its ions in the solution $\left( Q _{ sp }\right)$ becomes greater than its solubility product. If the solubility of $BaSO _4$ in water is $8 \times 10^{-4} mol dm ^{-3}$, calculate its solubility in $0.01 mol dm ^{-3}$ of $H _2 SO _4$.
✓

Answer


Image
Given solubility of $BaSO _4$ is $8 \times 10^{-4} mol dm ^{-3}$.
Therefore, for $BaSO _4$ in water, $K _{ sp }=\left[ Ba ^{2+}\right]\left[ SO _4^{2-}\right]=(S)(S)=S^2$
$
\therefore K_{s p}=\left(8 \times 10^{-4}\right)^2=64 \times 10^{-8} \ldots(1)
$
The expression for solubility product ( $K _{ sp }$ ) in the presence of sulphuric acid will be as follows:
$
K^{\prime} sp=(S)(S+0.01)\ldots(2)
$
Since the value of $K _{ sp }$ will not change in the presence of sulphuric acid.
Therefore, from (1) and (2), we have,
$
\begin{aligned}
& (S)(S+0.01)=64 \times 10^{-8} \\
& S^2+0.01 S=64 \times 10^{-8} \\
& S^2+0.01 S-64 \times 10^{-8}=0
\end{aligned}
$
$\begin{aligned} & \Rightarrow S=\frac{-0.01 \pm \sqrt{(0.01)^2+\left(4 \times 64 \times 10^{-8}\right)}}{2} \\ & \Rightarrow \frac{-0.01 \pm \sqrt{10^{-4}+\left(256 \times 10^{-8}\right)}}{2} \\ & \Rightarrow \frac{-0.01 \pm \sqrt{1.0256 \times 10^{-4}}}{2} \\ & \Rightarrow \frac{-0.01 \pm 1.0127 \times 10^{-2}}{2} \\ & \Rightarrow \frac{-0.01-1.0127 \times 10^{-2}}{2}, \frac{-0.01+1.0127 \times 10^{-2}}{2} \\ & \Rightarrow-1.006 \times 10^{-2}, 6.35 \times 10^{-5}\end{aligned}$
Concentration can never be negative. Hence required concentration is $6.35 \times 10^{-5} mol dm ^{-3}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "5 Marks Questions" from Model Paper 9→Model Paper 9 — all question types→Chemistry STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

  1. Define solubility product. Write solubility product expression in terms of molar solubility for $FeCl_3$
  2. What is the effect of temperature on solubility of gases in liquids?
  3. Equilibrium constant for the reaction is $4.0$. What will be the equilibrium constant for the reverse reaction.
  4. Calculate the pH of $10^{-8}M$ HCl solution.
→
Classify the following substances into oxidising and reducing agents:
  1. Carbon.
  2. Ozone.
  3. Nascent hydrogen.
  4. Nitric acid.
  5. Chlorine.
→
What will be the work done on an ideal gas enclosed in a cylinder, when it is compressed by a constant external pressure, $p_{ext}$​​​​​​​ in a single step as shown in Fig. Explain graphically.
→
i. A vessel of $1.00 dm ^3$ capacity contains $16.00$ g of oxygen and $8.00$ g of hydrogen at $17^{\circ} C$. Calculate the partial
ii. According to kinetic molecular theory, explain why gases exert pressure?
iii. How is isotherm at critical temperature of a gas different from those at lower temperatures?
→
Four moles of $\mathrm{PCl}_5$ are heated in a closed $4 \mathrm{dm}^3(\mathrm{~L})$ container to reach equilibrium at 400 K . At equilibrium $50 \%$ of $\mathrm{PCl}_5$ is dissociated. What is the value of $\mathrm{K}_{\mathrm{c}}$ for the dissociation of $\mathrm{PCl}_5$ into $\mathrm{PCl}_3$ and $\mathrm{Cl}_2$ at 400 K .
→
What is buffer solution? How many types of buffer solution are there? Explain with examples.
→
Explain with reasons the increasing order of energy of different orbitals in multielectron atoms.
→
  1. Calculate the kinetic energy of an electron in second Bohr orbit of hydrogen atom. [$a_0$ is Bohr radius].
  2. Out of the d-orbials which does not have four lobes?
  3. What is physical significance of $\Psi^2?$
→
Discuss the trend of the following:
The solubility and the nature of oxides, of Group 2 elements.
→
What is distillation? Explain different types of distillation.
→