Answer:
75 kJ/mol
Explanation:
The reactions occur at a rate, which means that the concentration of the reagents decays at a time. The rate law is a function of the concentrations and of the rate constant (k) which depends on the temperature of the reaction.
The activation energy (Ea) is the minimum energy that the reagents must have so the reaction will happen. The rate constant is related to the activation energy by the Arrhenius equation:
ln(k) = ln(A) -Ea/RT
Where A is a constant of the reaction, which doesn't depend on the temperature, R is the gas constant (8.314 J/mol.K), and T is the temperature. So, for two different temperatures, if we make the difference between the two equations:
ln(k1) - ln(k2) = ln(A) - Ea/RT1 - ln(A) + Ea/RT2
ln (k1/k2) = (Ea/R)*(1/T2 - 1/T1)
k1 = 8.3x10⁸, T1 = 142.0°C = 415 K
k2 = 6.9x10⁶, T2 = 67.0°C = 340 K
ln(8.3x10⁸/6.9x10⁶) = (Ea/8.314)*(1/340 - 1/415)
4.8 = 6.39x10⁻⁵Ea
Ea = 75078 J/mol
Ea = 75 kJ/mol
Answer:125ml - volume of phosphoic acid
Explanation:
The equation of the reaction is
H3PO4 + 3 NaOH ---> Na3PO4 + 3H2O
Such that I mole of H3PO4 reacts with 3 moles of NaOH to produce the products above.
Given that
M1= Molarity of phosphoric acid = 7.48x10^-2 M
n1= number of moles of phosphoric acid = 1
V1=? ml
M2= Molarity of Sodium hydroxide =0.244 M
V2= volume of sodium hydroxide= 115ml
n2=number of moles of sodium hydroxide = 3
Using the Dilution equation formulae,
M1V1/n1 = M2V2/n2
7.48X10-2 x V1 /1= 0.244M x 115ml/3
V1=0.244Mx115mlx1/0.0748M X 3
V1= 28.06/0.2244= 125.04ml
V1=125.04ml rounded up to 125ml
Hey there!:
Density = 0.798 g/mL
Volume = 16.9 mL
Therefore:
Mass = density * volume
Mass = 0.798 * 16.9
Mass = 13.4862 g
Answer:
The best definition is: "Buffer capacity is the amount of acid or base that can be added to a buffer without destroying its effectiveness"
Explanation:
A buffer is a solution that is somewhat resist to pH changes by reacting with acids and bases that may be added into the solution. It's capacity is the amounto of acid or base that can be added into solution without much change in pH.
So the best definition is: "Buffer capacity is the amount of acid or base that can be added to a buffer without destroying its effectiveness"