Answer:
3.51
Explanation:
Before any sodium hydroxide has been added, the pH is that of the aqueous hydrofluoric acid solution.
HF is a weak acid that dissociates according to the following equation.
HF(aq) ⇄ H⁺(aq) + F⁻(aq) Ka = 6.76 × 10⁻⁴
We can find [H⁺] using the following expression.
[H⁺] = √(Ca × Ka)
where
Ca: concentration of the acid
Ka: acid dissociation constant
[H⁺] = √(Ca × Ka)
[H⁺] = √(0.458 × 6.76 × 10⁻⁴)
[H⁺] = 3.10 × 10⁻⁴ M
The pH is:
pH = -log [H⁺]
pH = -log 3.10 × 10⁻⁴ = 3.51
Answer: 17.78g
Explanation:
Assume there is no heat exchange with the environment, then the amount of heat taken by the steel rod, Q(s), is equal to the amount of heat lost by the water, Q(w), but with opposite sign.
Q(s) = -Q(w)
Remember, Q = mc(ΔΦ)
Where Q = amount of heat
m = mass of steel
c = specific heat capacity of steel
ΔΦ = Initial temperature T1 - Final temperature T2
Q = mc(T1-T2)
Recall, Q(s) = -Q(w). Then,
m(s)*c(s)*(T1s - T2s) = - m(w)*c(w)*(T1w - T2w)
Substituting each values
Note: m(w) = volume of water*density = 75mL*1g/mL = 75g
m(s)*0.452*(21.5-2) = -75*4.18*(21.5-22)
m(s)*8.814 = 156.75
m(s) = 156.75/8.814
m(s) = 17.78g
Therefore, the mass of steel is 17.78g
<h3>the balanced chemical reaction would be :</h3>
CH4 + 2O2 =》CO2 + 2H2O
Answer:
the balanced chemical reaction is provided above .
Explanation:
the given reaction is reaction of methane with oxygen ( or burning of methane in presence of oxygen )
it is highly exothermic, because high amount of heat is evolved in this reaction
Answer:
A
Explanation:
Polypeptides such as proline and glycine are capable of making a sharp turn called a reverse turn due to the suitability and flexibility of their cyclic structure
