Answer:
Explanation:
Zn + 2HCl = ZnCl₂ + H₂
A ) mole of Zn = 2.65 / 65
= .04 mol
mole of HCl required = .04 x 2 mol
.08 mol
If v be the volume required
v x 6 = .08
v = .0133 liter
= 13.3 cc
B )
volume of gas at NTP :
moles of gas obtained = .04 moles
= 22.4 x .04 liter
= .896 liter
we have to find this volume at given temperature and pressure
= 1.175 liter.
C )
.04 mole of zinc chloride will be produced
mol weight of zinc chloride
= 65 + 35.5 x 2
= 136 gm
.04 mole = 136 x .04
= 5.44 gm
Answer:
77 L of water can be made.
Explanation:
Molar mass of = 32 g/mol
So, 55 g of =
mol of
= 1.72 mol of
As hydrogen is present in excess amount therefore is the limiting reagent.
According to balanced equation, 1 mol of produces 2 mol of
.
So, 1.72 mol of produce
mol of
or 3.44 mol of
.
Let's assume gas behaves ideally at STP.
Then, , where P, V, n, R and T represents pressure, volume, no. of moles, gas constant and temperature in kelvin scale respectively.
At STP, pressure is 1 atm and T is 273 K.
Here, = 3.44 mol and R = 0.0821 L.atm/(mol.K)
So,
Option (b) is correct.
Answer:
pH of buffer after addition of 1 mL of 0,1 M HCl = 7,0
Explanation:
It is possible to use Henderson–Hasselbalch equation to estimate pH in a buffer solution:
pH = pka + log₁₀
Where A⁻ is conjugate base and HA is conjugate acid
The equilibrium of phosphate buffer is:
H₂PO₄⁻ ⇄ HPO4²⁻ + H⁺ Kₐ₂ = 6,20x10⁻⁸; pka=7,2
Thus, Henderson–Hasselbalch equation for 7,00 phosphate buffer is:
7,0 = 7,2 + log₁₀
Ratio obtained is:
0,63 =
As the problem said you can assume [H₂PO₄⁻] = 0,1 M and [HPO4²⁻] = 0,063M
As the amount added of HCl is 0,001 M the concentrations in equilibrium are:
H₂PO₄⁻ ⇄ HPO4²⁻ + H⁺
0,1 M +x 0,063M -x 0,001M -x -<em>because the addition of H⁺ displaces the equilibrium to the left-</em>
Knowing the equation of equilibrium is:
Replacing:
6,20x10⁻⁸ =
You will obtain:
x² -0,064 x + 6,29938x10⁻⁵ = 0
Thus:
x = 0,063 → No physical sense
x = 0,00099990
Thus, [H⁺] in equilibrium is:
0,001 M - 0,00099990 = 1x10⁻⁷
Thus, pH of buffer after addition of 1 mL of 0,1 M HCl =
-log₁₀ [1x10⁻⁷] = 7,0
A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. In this example you can see its effect!
I hope it helps!