Which atomic property is different in each isotope of an element?
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Given that, an experiment to measure the enthalpy change for the reaction of aqueous copper(II) sulfate, CuSO4(aq) and zinc, Zn(s) was carried out in a coffee cup calorimeter; the heat of the reaction in the whole system is calculated to be 2218.34 kJ
Heat of reaction (i.e enthalpy of reaction) is the quantity of heat that is required to be added or removed when a chemical reaction is taken place in order to maintain all of the compounds present at the same temperature.
The formula used to calculate the heat of the reaction can be expressed as follows:
Q = mcΔT
where:
- Q = quantity of heat transfer
- m = mass
- c = specific heat of water = 4.18 kJ/g °C (constant)
- ΔT = change in temparature
From the information given:
- The initial temperature (T₁) = 25° C
- The final temperature (T₂) = 91.5° C
∴
The change in temperature i.e. ΔT = T₂ - T₁
ΔT = 91.5° C - 25° C
ΔT = 66.5° C
The number of moles of CuSO₄ = 1.00 mol/dm³ × 50.0 cm³
= 0.05 moles
- Since the molar mass of CuSO₄ = 159.609 g/mol
Then;
Using the relation:
By crossing multiplying;
mass of CuSO₄ = number of moles of CuSO₄ × molar mass of CuSO₄
mass of CuSO₄ = 0.05 moles × 159.609 g/moles
mass of CuSO₄ = 7.9805 grams
∴
Using the formula from above:
Q = mcΔT
Q = 7.9805 g × 4.18 kJ/g °C × 66.5° C
Q = 2218.34 kJ
Therefore, we can conclude that the heat of the reaction is 2218.34 kJ
Learn more about the chemical reaction here:
pH=4.625
The classification of this sample of saliva : acid
<h3>Further explanation</h3>The water equilibrium constant (Kw) is the product of concentration
the ions:
Kw = [H₃O⁺] [OH⁻]
Kw value at 25° C = 10⁻¹⁴
It is known [OH-] = 4.22 x 10⁻¹⁰ M
then the concentration of H₃O⁺:
pH=-log[H₃O⁺]
Saliva⇒acid(pH<7)
Answer:
(a) 0.779 mol Cr₂O₃
(b) 118 g Cr₂O₃
Explanation:
Step 1: Convert 156 g Cr₂S₃ to moles
Cr Molar Mass - 52.00 g/mol × 2 = 104.00 g/mol
S Molar Mass - 32.07 g/mol × 3 = 96.21 g/mol
156 g Cr₂S₃ ÷ 200.21 g/mol = 0.779182 mol Cr₂S₃
Step 2: Find conversion from Cr₂S₃ to Cr₂O₃
1 mol Cr₂S₃ equals 1 mol Cr₂O₃
Step 3: Use Dimensional Analysis
0.779182 mol Cr₂S₃ · = 0.779182 mol Cr₂O₃
0.779182 mol Cr₂O₃ ≈ 0.779 mol Cr₂O₃ (3 significant figures)
Step 4: Convert moles to grams
Cr Molar Mass - 52.00 g/mol × 2 = 104.00 g/mol
O Molar Mass - 16.00 g/mol × 3 = 48.00 g/mol
0.779182 mol Cr₂O₃ · 152.00 g/mol = 118.436 g Cr₂O₃
118.436 g Cr₂O₃ ≈ 118 g Cr₂O₃ (3 significant figures)