Answer:
2.25g of NaF are needed to prepare the buffer of pH = 3.2
Explanation:
The mixture of a weak acid (HF) with its conjugate base (NaF), produce a buffer. To find the pH of a buffer we must use H-H equation:
pH = pKa + log [A-] / [HA]
<em>Where pH is the pH of the buffer that you want = 3.2, pKa is the pKa of HF = 3.17, and [] could be taken as the moles of A-, the conjugate base (NaF) and the weak acid, HA, (HF). </em>
The moles of HF are:
500mL = 0.500L * (0.100mol/L) = 0.0500 moles HF
Replacing:
3.2 = 3.17 + log [A-] / [0.0500moles]
0.03 = log [A-] / [0.0500moles]
1.017152 = [A-] / [0.0500moles]
[A-] = 0.0500mol * 1.017152
[A-] = 0.0536 moles NaF
The mass could be obtained using the molar mass of NaF (41.99g/mol):
0.0536 moles NaF * (41.99g/mol) =
<h3>2.25g of NaF are needed to prepare the buffer of pH = 3.2</h3>
No because it burns the food that u had and leaves it more space?????? I
Answer:
When ΔS > ΔH/ T, then the reaction will proceed forward
Explanation:
- The entity that determines the whether a reaction will occur on its own in the forward direction (Spontaneity or Feasibility) is Gibb's free energy.
- Gibb's free energy is the energy available to do work. It is denoted as 'G'. It cannot be easily measured. The change (ΔG) can only be measured. ΔG = ΔH - TΔS
when ΔG is positive, The reaction is not spontaneous (reaction will not occur on its own)
When ΔG is negative, The reaction is spontaneous (reaction will occur on its own)
When ΔG is zero, the reaction is in equilibrium
Option A and E are not correct. ΔH (Enthalpy) cannot determine spontaneity
Option C and D cannot alone determine spontaneity of reaction
For reaction to be spontaneous, TΔS > ΔH
Therefore, ΔS > ΔH/T
The symbol for the hydroxide ion is OH-
