Answer:
C. density
Explanation:
Density has to do with weight. Hen you pick up the Styrofoam model, you would notice how much more light it is opposed to the granite model.
The value of delta H° for aniline = 6415 Kj/mol
<u><em>calculation</em></u>
Step 1: find heat
Q (heat) = C (specific heat capacity) x ΔT (change in temperature)
C= 4.25 kj/c°
ΔT = 69.8-29.5 = 40.3 c°
Q= 4.25 kj/c x 40.3 c = 171.28 kj
Step 2: find the moles of aniline
moles = mass/molar mass
= 2.49 g/ 93.13 g/mol =0.0267 moles
Step 3: find delta H
171.28 kj/0.0267 mol = 6415 kj/mol
since the reaction is exothermic delta H = 6415 Kj/mol
In a number with decimal, zeroes to the right of last non-zero digit are significant.
Hence there are 4 significant digits in 3.140.
Hope this helps, have a great day ahead!
First, we need to get the concentration of [NaH2PO4]:
[NaH2PO4] =( mass / molar mass ) * volume L
when we have mass NaH2PO4 = 6.6 g & molar mass = 120g/mol & V = 0.355 L
So by substitution:
[NaH2PO4] = (6.6g / 120g/mol) * 0.355 L = 0.0195 M
then, we need to get the concentration of [Na2HPO4]:
[Na2HPO4]= (mass / molar mass ) * volume L
So by substitution:
[Na2HPO4] = (8g/ 142g/mol) * 0.355 L = 0.02 M
and when Pka of the 2nd ionization of phosphoric acid = 7.21
So by substitution in the following formula, we can get the PH:
PH = Pka + ㏒[A]/[AH]
∴PH = 7.21 + ㏒[0.02]/[0.0195]
∴ PH = 7.2
I think air but if wrong sorry
