Show how acids ionize in an aqueous solution? Show how each of the following acids ionize in aqueous solution.
1. HI
2. HF
3. C6H5COOH
I know that the beginning of each equation should look like this:
1. HI (aq) + H20 (l) -> ?
2. HF (aq) + H2O (l) -> ?
3. C6H5COOH (aq) + H2O (l) -> ?
can anybody offer some insight??? Im not sure where to go from here...
Dr.A replied: "HI (aq) + H2O (l) ---> H3O+ (aq) + I- (aq)
HF (aq) + H2O (l) ----> H3O+ (aq) + F- (aq)
C6H5COOH (aq) + H2O (l) ----> C6H5COO- (aq) + H3O+ (aq)"
bmanhat replied: "By definition acids are H+ donors so in water they will release an H+ and form the conjugate base and the acid h3O"
percent ionized!? Benzoic acid is a weak acid that has antimicrobial properties. Its sodium salt, sodium benzoate, is a preservative found in foods, medications, and personal hygiene products. Benzoic acid dissociates in water:
C6H5COOH + H2O ==== H+ and C6H5COO-
The pKa of this reaction is 4.2. In a 0.505 M solution of benzoic acid, what is the fraction of the total acid that is ionized?
what is the % ionized= ?
Dr.A replied: "Ka = 10^-4.2 =6.3 x 10^-5 M
6.3 x 10^-5 = x^2 / 0.505-x
x = 0.00564
0.00564 x 100 / 0.505 = 1.1 %"
Please help me to calculate pH!? My question is:
I want to do a buffer with benzoic acid and NaOH, and I will call this buffer when its finish for “Solution A”.
I want to have 200 ml of the buffer, and I have 1,32 g benzoic acid and 24 ml of 1,00 M NaOH.
C6H5COOH + OH- C6H5COOH + H2O
1. first i want to calculate the buffer pH, and i have done like this:
Vtot= 200*10-3ml
mbenzoic=1,32 g
Mwbenzoic=122g/mol
nbenzoic= 0,01 mol
VNaOH= 24*10-3 ml
CNaOH= 1 M
nNaOH= 0,024 mol
Then I calculated the concentration in 200 ml:
CNaOH= n/V => 0,024/200*10-3 = 0,12 M
Cbenzoic= n/V => 0,01/200*10-3= 0,05 M
Now I will use Henderson–Hasselbalch equation..
And the pKa for benzoic acid is 4,19.. So with the Henderson–Hasselbalch equation i will get the pH at the buffer: 6,59.
Have i thinking right now?
2. My other question is that i want to calculate pH if I take 20 ml “Solution A” (the solution above) and establish 1ml, 1M NaOH. How do I calculate this pH?
Is it the concentration for benzoic acid that I use for the calculation?
Dr.A replied: "moles acid = 1.32 g/ 122 g/mol= 0.0108
moles NaOH = 0.024
C6H5COOH + OH- => C6H5COO- + H2O
all the acetic acid has been used up
moles OH- in excess = 0.024 - 0.0108=0.0132
[OH-]= 0.0132 / 0.200 L= 0.066 M
pOH = - log 0.066 =1.18
pH = 14 - 1.18 =12.82
Moles NaOH added = 1 x 10^-3 L x 1 M = 1 x 10^-3
moles OH- in excess = 0.0132 + 1 x 10^-3 =0.0142
total volume = 0.201 L
[OH-]= 0.0142/ 0.201 =0.0706 M
pOH = 1.15
pH = 12.85"
Balancing Equations Help & Question!? Could somebody please balance this equation, & possibly help with the general question? (equation to balance:) C6H5COOH-->H2O + CO2. The Actual question is : When benzoic acid is burned, the enthalpy of combustion is -3323.6 kJ/mol. Use the info & tabulated values of the standard enthalpies of formation of water (liquid) and carbon dioxide to claculate the standard enthalpy of formation of benzioc acid. ( The enthalpy of water = -285.8kJ/mol, and the standard enthalpy of carbon dioxide is = -393.5kJ/mol) Thanks a bunch, If you don't understand or know how to do the question, please at least help me balance the equation. Thankyou : )
squanto replied: "Don't forget, you don't have to use a whole number to balance an equation. Often times, water needs to be a half mole when CO2 is a product."
A sample of C6H5COOH weighing 1.221g was placed in a bomb calorimeter. ? This is ignited in a pure O2 atmosphere. A temperature rise from 25.24C to 31.67C was noted. The heat capacity of the calorimeter was 5.020kJ/C and the combustion products were CO2 and H2O. Calculate the change in H in kJ/mol for the reaction. If someone answers this, can you please show your work because I keep getting -3940kJ/mol when the answer is -3230kJ/mol. Thanks
jpsazii replied: "-3229 kJ/mol
First of all, you have 1.221g C6H5COOH (benzoic acid). Since each carbon has a mass of 12.01, each oxygen has a mass of 16.00, and each hydrogen has a mass of 1.01, this compound has a molar mass of 122.13 g/mol. That means that 1.221 g is 1.221/122.13 = 0.009998 mol.
Now take the change in temperature, 31.67-25.24 = 6.43. Since the heat capacity of the calorimeter is 5.020 kJ/C, the change in enthalpy can be found by taking the product of the change in temperature and the heat capacity. Since heat is given off, we give this a - sign. -(6.43 C)(5.020 kJ/C) = -32.2786 kJ.
OK, so we know the change in enthalpy and the number of moles, so take the ratio.
-32.2786 kJ/0.09998 mol = -3229 kJ/mol (to 4 significant figures)
I hope this helps!"
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