1-HI, H2 and I2 are placed in a container at 458 ° C. Among these substances 2H (g) <----> H2 (g) + I2 (g) [HI] = 0.15 M when the balance is established. Since K = 2.06 × 10 ^ -2 is given for reaction at this temperature, which of the following H2 concentrations in equilibrium is?
a) 4.94×10^-2
b) 1.78×10^-2
c) 2.47×10^-2
d) 1.17×10^-2
e) None
2-Which of the following salt solutions shows base?
a) NH4Cl
b) Mg(ClO4)2
c) HCL
d) K3PO4
e) CaCl2
3- Which of the statements given in balance is wrong?
a) It is a dynamic event where the speeds of two opposite trends are equal.
b) The speed of the forward reaction is equal to the reaction speed of the backward.
c) The magnitude of the numerical value of the equilibrium constant indicates the equilibrium position, which indicates the quantity of the reactant or products.
d) In reactions involving more than one step, the equilibrium constant of the total reaction is equal to the product of the equilibrium constants in each step.
e) Concentrations are stable due to the halting of all activities.
4- Which one is required for a gas phase reaction to take place?
|. Molecules collide in the appropriate direction and direction.
||. Molecules colliding in the appropriate direction exceed the threshold energy.
|||. Adding substance to the reaction vessel.
a) Only ||
b) | and |||
c) Only |
d) || and |||
e) | and ||
5- Which of the following is wrong?
a) NaHCO3 solution is amphoteric.
b) CH3NH3 ^ - / CH3NH2 is a double conjugated acid-base pair.
c) pH = 10 for 1 × 10 ^ -10 M HCl solution.
d) The dissociation constant of water varies with Kw temperature.
e) the salt of the weak base is usually weak acid.
6- The resolution of CaF2 (Keq = 5.3 × 10 ^ -9) will be the lowest of the following?
a) 0.1 M NaCl
b) H2O
c) 0.1 M NaF
d) 0.1 M HNO3
e) 0.1 M Ca(Na3)2
I think you made a typo. I think you meant to write
2HI(g) <----> H2 (g) + I2
Also, the English and wording is a little confusing. I assume you mean that [HI] = 0.15 M at the beginning of the reaction and you want to calculate [H2] at equilibrium.
................... 2HI(g) <----> H2 (g) + I2
I.....................0.15.............0.............0
C......................-2x.............x.............x
E..................0.15-x............x..............x
K = 2.06E-2 = (H2)(I2)/(HI)^2. Plug in the numbers from the E line (equilibrium) and solve for x = (H2) = (I2)
Post your work if you get stuck. Let me know if I have interpreted the problem incorrectly.
2-Which of the following salt solutions shows base?
a) NH4Cl
b) Mg(ClO4)2
c) HCL
d) K3PO4
e) CaCl2
The correct answer is that students are supposed to know if the cation is strong enough, in solution, to pull the OH of water (HOH) away from the H OR if the anion is strong enough to pull the H away from the OH. The problem is I don't how the students' are supposed to know that.When I was a student I didn't know it so I came up with a procedure to answer the question but if you tell your prof this procedure you will be laughed out of the classroom. BUT, this will give you the correct answer every time. Here is how it works. It's long to explain but here goes. I'll do this for a couple, say CaCl2 and K3PO4. The others are yours to try.
I write the equation for the salt + H2O and do a double replacement, like this.
CaCl2 + 2HOH ==> Ca(OH)2 + 2HCl
Then I ask myself this. Is Ca(OH)2 a strong or weak base? Is HCl a strong or weak acid? HCl is a strong acid. Ca(OH)2 is a weak base (actually quite strong but it does have Ksp) so THIS SALT, CaCl2, when place in solution, WILL BE ACID BECAUSE HCl is a stronger acid than Ca(OH)2 is a base.
For NaCl=== NaCl + HOH --> NaOH + HCl . NaOH is a strong base, HCl is a strong acid; therefore, the NaCl solution will be neutral.
K3PO4 + 3HOH ==> 3KOH + H3PO4
KOH is a strong base; H3PO4 is a weak acid. The solution of K3PO4 will be basic. This should give you the idea how to do these. With practice you will learn that cations like Na, K, Li, etc are too weak to break the HOH bond so those cations don't hydrolyze. Anions like Cl^-, Br^-, I^- are too weak to break the HOH bond so they don't hydrolyze. Anions, like acetate, phosphate or cations like NH4^+ do hydrolyze. You will learn, for example, that NH4Cl will be acidic. NH4^+ hydrolyzes; Cl^- does not so
NH4^+ + HOH ==> NH3 + H3O^+. That H3O^+ tells you immediately that this is an acidic solution. Hope this helps.
3. When you write 'balance' do you mean equilibrium. Read in your text or notes (or look on Google) to see about reactions in equilibrium. That should help you answer the questions.Note that equilibrium is a dynamic process, always moving (never stopping) and has forward and reverse reactions that occur continuously in both directions and equilibrium occurs when the speed of the forward reaction equals the speed of the reverse reaction.
4. Surely this is available in your text, notes or on Google.
5. What is your problem in answering this?
6. What do you mean by 'resolution'? Could you mean solubility?
By question 5, I mean that a, b ,c d and e are expressions, and there is one wrong between them. And in the 6 question i mean solubility.
5- Which of the following is wrong?
a) NaHCO3 solution is amphoteric.
b) CH3NH3 ^ - / CH3NH2 is a double conjugated acid-base pair.
c) pH = 10 for 1 × 10 ^ -10 M HCl solution.
d) The dissociation constant of water varies with Kw temperature.
e) the salt of the weak base is usually weak acid.
6- The resolution of CaF2 (Keq = 5.3 × 10 ^ -9) will be the lowest of the following?
a) 0.1 M NaCl
b) H2O
c) 0.1 M NaF
d) 0.1 M HNO3
e) 0.1 M Ca(Na3)2
5 and 6.
Ok. Yes 5 does have one wrong answer. But you should know how to find the one incorrect answer. What is it you don't understand that would allow you to answer question 5. By the way, you have a typo in answer b. I assume you meant
b) CH3NH3 ^+/ CH3NH2 is a double conjugated acid-base pair. This is a correct statement with my correction. There is one other incorrect statement.
Same thing about question 6. What is keeping you from answering?