<u>Answer:</u> The mass of 97 % of NaOH solution required is 114.33 g
<u>Explanation:</u>
To calculate mass of a substance, we use the equation:
We are given:
Density of 10 % solution = 1.109 g/mL
Volume of 10% solution = 1 L = 1000 mL (Conversion factor: 1 L = 1000 mL)
Putting values in above equation, we get:
The mass of 10 % solution is 1109 g.
To calculate the mass of concentrated solution, we use the equation:
where,
are the concentration and mass of concentrated solution.
are the concentration and mass of diluted solution.
We are given:
Putting values in above equation, we get:
Hence, the mass of 97 % of NaOH solution required is 114.33 g
Answer:
Explanation:
Concentration: i is defined as the mole per litre.
mole=0.15
volume=400 ml=0.4 litre
Answer:
-800 kJ/mol
Explanation:
To solve the problem, we have to express the enthalpy of combustion (ΔHc) in kJ per mole (kJ/mol).
First, we have to calculate the moles of methane (CH₄) there are in 2.50 g of substance. For this, we divide the mass into the molecular weight Mw) of CH₄:
Mw(CH₄) = 12 g/mol C + (1 g/mol H x 4) = 16 g/mol
moles CH₄ = mass CH₄/Mw(CH₄)= 2.50 g/(16 g/mol) = 0.15625 mol CH₄
Now, we divide the heat released into the moles of CH₄ to obtain the enthalpy per mole of CH₄:
ΔHc = heat/mol CH₄ = 125 kJ/(0.15625 mol) = 800 kJ/mol
Therefore, the enthalpy of combustion of methane is -800 kJ/mol (the minus sign indicated that the heat is released).
Answer:
The Moon weighs about 7.349*10^22 kg
How much does “an elephant” weigh? Grown-up elephants vary between 1.7 tons (small wood elephant cow) and 6 tons (big African elephant bull). Let us pick 2.720 tons or 2720 kg as an average weigh one, this is valid for Asian elephants.
A mole of elephants weighs 6.022 * 10^23 x 2720 kg = 1.638 * 10^27 kg.
That is 1,638 * 10^27 / 7,349*10^22 = 22289 times more.
Answer:
1. ΔE = 0 J
2. ΔH = 0 J
3. q = 3.2 × 10³ J
4. w = -3.2 × 10³ J
Explanation:
The change in the internal energy (ΔE) and the change in the enthalpy (ΔH) are functions of the temperature. If the temperature is constant, ΔE = 0 and ΔH = 0.
The gas initially occupies a volume V₁ = 20.0 L at P₁ = 3.2 atm. When the pressure changes to P₂ = 1.6 atm, we can find the volume V₂ using Boyle's law.
P₁ × V₁ = P₂ × V₂
3.2 atm × 20.0 L = 1.6 atm × V₂
V₂ = 40 L
The work (w) can be calculated using the following expression.
w = - P . ΔV
where,
P is the external pressure for which the process happened
ΔV is the change in the volume
w = -1.6 atm × (40L - 20.0L) = -32 atm.L × (101.325 J/1atm.L) = -3.2 × 10³ J
The change in the internal energy is:
ΔE = q + w
0 = q + w
q = - w = 3.2 × 10³ J
