Answer: second option: 1.70 to 1.40
Explanation:
1) The definition and formula of pH is - log [H₃O⁺]
2) So, if the original concentration is x and the increased concentration is 2x, you get:
pHi = - logx
pHf = - log 2x = - log 2 - logx
⇒ pHf - pHi = - log2 - logx - (- logx) = - log2 ≈ - 0.30
⇒ pHi - pHf = 0.30 This is the pH of the final solution (with double concentration of hydronium ions) is 0.30 points lower than the pH of the initial pH.
3) The only choice that shows a decrease of 0.30 in the pH is the second option: 1.70 to 1.40. So that is the answer.
Answer:
T = 100.63 °C
Explanation:
To solve this question, we need to know what are we talking about here. In this case, we want to know the boiling point of a solution with Urea in water. This is a colligative property, so, the expression to use to calculate that is the following:
ΔT = m * K / MM * kg water (1)
Where:
ΔT: difference of temperatures (Tb of solution - Tb water)
m: mass of the urea
K: ebulloscopic constant of the water (0.52 ° C / m)
MM: molecular mass of urea
The boiling point of water is 100 °C, we have the mass of the urea, but not the molar mass. The urea has the formula CH₄N₂O, so the molar mass can be calculated using the atomic mass of the elements (I will use a rounded number for this):
MM = 12 + (4*1) + (2*14) + 16 = 60 g/mol
Now, we can calculate the ΔT and then, the boiling point of the solution:
ΔT = 12 * 0.52 / 60 * 0.165
ΔT = 6.24 / 9.9
ΔT = 0.63 °C
the value of ΔT is a difference between the boling point of water and the solution so:
ΔT = Ts - Tw
Ts = ΔT + Tw
Replacing we have:
Ts = 100 + 0.63
<h2>
Ts = 100.63 ° C</h2>
With creates the waves. The stronger the wind the larger and more powerful the waves are.
Solution : As they have uniform composition throughout they are considered as homogeneous mixture. Both samples are mixture of two metals (gold and palladium) thus are alloys.
Answer:
-145.2kJ
Explanation:
Enthalpy is an extensive property as its value depends on the amount of substance present in the system.
If the enthalpy for one mole of methanol = -726 kJ/mol;
The Enthalpy for 0.2 mol is given as;
Enthalpy = 0.200 * 726
Enthalpy = -145.2kJ
It would take -145.2kJ for 0.200 mol of methanol to undego the combustion reaction.
