Answer:
A) pH = 8.11
B) pH = 7.96
Explanation:
The pH of buffer is calculated using Henderson Hassalbalch's equatio, which is
![pH=pKa+log\frac{[salt]}{[acid]}](https://tex.z-dn.net/?f=pH%3DpKa%2Blog%5Cfrac%7B%5Bsalt%5D%7D%7B%5Bacid%5D%7D)
pKa = -logKa = -log(3.0 ✕ 10⁻⁸)
pKa = 7.5
[salt] = 0.667
[Acid] = 0.214
A) If the solution is halved it means the concentration of both salt and acid will be the same.
The volume will change
Number of moles of acid = molarity X volume = 0.214 X 25 = 5.35 mmol
Number of moles of salt = molarity X volume = 0.667 X 25 = 16.68 mmol
moles of NaOH added = molarity X volume = 0.100 X 10 = 1 mmol
These moles of NaOH will react with acid to give same amount of salt and thus the moles of acid will decrease
New moles of acid = 5.35 - 1 = 4.35
New moles of salt = 16.68 + 1 = 17.68
the new pH will be
B)
moles of HCl added = molarity X volume = 0.100 X 10 = 1 mmol
These moles of HCl will react with salt to give same amount of acid and thus the moles of salt will decrease
New moles of acid = 5.35 + 1 = 6.35
New moles of salt = 16.68 - 1 = 15.68
the new pH will be
Answer: El conocimiento científico es un saber crítico (fundamentado), metódico, verificable, sistemático, unificado, ordenado, universal, objetivo, comunicable (por medio del lenguaje científico), racional, provisorio y que explica y predice hechos por medio de leyes.
Explanation: El conocimiento científico es un saber crítico (fundamentado), metódico, verificable, sistemático, unificado, ordenado, universal, objetivo, comunicable (por medio del lenguaje científico), racional, provisorio y que explica y predice hechos por medio de leyes.
Answer:
38.9%
Explanation:
below, determine the mass percent of Fe3+ in a 0.6450 g sample of iron ore, if 22.40 mL of a 0.1000 M stannous chloride, SnCl2(aq), solution is required to completely react with the Fe3+ present in the ore sample. The chemical equation for the reaction is
2 Fe3+ (aq) + Sn2+ (aq) →2Fe2+ (aq) + Snº+(aq).
O 19.40%
O 6.196%
O 38.79%
O 9.697%
2 Fe3+ (aq) + Sn2+ (aq) →2Fe2+ (aq) + Snº+(aq).ole of Sn2+
for every mole of Sn2+, tere are 2 moles of Fe3+
- 22.4/1000L of 0.1000 M Sn2+ = 22.4 X 0.10/1000 = 0.00224 mole
so there are 0.00224 X 2= 0.00448 moles Fe3+
iron atomic mass is 56
56 X 0.00448 = 0.251 gm Fe3+
so the mass % of the Fe3+ in the 0.645 gm iron ore sample is
(0.251/0.645) X 100 = 38.9%
Answer : Cadmium sulfide (CdS) precipitate is formed.
Explanation :
When the sodium sulfide, 
is mixed with cadmium sulfate, 
then cadmium sulfide precipitate and sodium sulfate, 
is formed. The cadmium sulfide is insoluble in hot and cold water but sodium sulfate is soluble in water.
The balanced chemical reaction will be,
This reaction is an example of double displacement reaction in which the cation and anion of the two reactants exchange their places to give two new products.
This is a chemical reaction where the two clear solutions mixed to produce a bright yellow colored precipitate of cadmium sulfide.
Charles law gives the relationship between temperature and volume of gas.
It states that at a constant pressure, volume of gas is directly proportional to the temperature for a fixed amount of gas.
V/T = constant
where V- volume, T- temperature
V1/T1 = V2/T2
Where parameters for the first instance are on the left side and parameters for the second instance are on the right side of the equation
temperature should be in Kelvin for calculation
temperature in K = temperature in Celcius + 273
T1 = 137 °C + 273 = 410 K
substituting values in the equation
250 mL / 410 K = 425 mL /T2
T2 = 697 K
temperature in Celcius = 697 K - 273
temperature = 424 °C
