Answer:
You should not use an open flame to heat the solvent and the solvent should be heat in a stoppered flask to vapour away from the open flame
Explanation:
3s.f as that's what the numbers in the question are given to
So the answer is 0.978
Answer:
Mass of NaBr produced = 23.67 g
Explanation:
Given data:
Mass of AgBr = 42.7 g
Mass of NaBr produced = ?
Solution:
Chemical equation:
2Na₂S₂O₃ + AgBr → NaBr + Na₃(Ag(S₂O₃)₂
Number of moles of AgBr:
Number of moles = mass/molar mass
Number of moles = 42.7 g/ 187.7 g/mol
Number of moles = 0.23 mol
now we will compare the moles of AgBr with NaBr.
AgBr : NaBr
1 : 1
0.23 : 0.23
Mass of NaBr:
Mass = number of moles × molar mass
Mass = 0.23 mol × 102.89 g/mol
Mass = 23.67 g
Answer is: silicon isotope with mass number 28 has highest relative abundance, this isotope is the most common of these three isotopes.
Ar₁(Si) = 28; the average atomic mass of isotope ²⁸Si.
Ar₂(Si) =29; the average atomic mass of isotope ²⁹Si.
Ar₃(Si) =30; the average atomic mass of isotope ³⁰Si.
Silicon (Si) is composed of three stable isotopes, ₂₈Si (92.23%), ₂₉Si (4.67%) and ₃₀Si (3.10%).
ω₁(Si) = 92.23%; mass percentage of isotope ²⁸Si.
ω₂(Si) = 4.67%; mass percentage of isotope ²⁹Si.
ω₃(Si) = 3.10%; mass percentage of isotope ³⁰Si.
Ar(Si) = 28.086 amu; average atomic mass of silicon.
Ar(Si) = Ar₁(Si) · ω₁(B) + Ar₂(Si) · ω₂(Si) + Ar₃(Si) · ω₃(Si).
28,086 = 28 · 0.9223 + 29 · 0.0467 + 30 · 0.031.
Answer: The heat of combustion per mole for acetylene is 227.7 kJ/mol.
Explanation:
The combustion equation of acetylene is as follows.
Formula to calculate enthalpy of formation for a reaction is as follows.
![\Delta H^{o}_{rxn} = \sum \Delta H_{products} - \sum \Delta H_{reactants}\\\Delta H^{o}_{rxn} = [2\Delta H^{o}_{f}(CO_{2}) + \Delta H^{o}_{f} (H_{2}O)] - [\Delta H^{o}_{f}(C_{2}H_{2}) + \frac{5}{2} \Delta H^{o}_{f} O_{2}]\\-1299.5 = 2(-393.5) + (-285.8) - \Delta H^{o}_{f} (C_{2}H_{2})\\\Delta H^{o}_{f} (C_{2}H_{2}) = 227.7 kJ/mol](https://tex.z-dn.net/?f=%5CDelta%20H%5E%7Bo%7D_%7Brxn%7D%20%3D%20%5Csum%20%5CDelta%20H_%7Bproducts%7D%20-%20%5Csum%20%5CDelta%20H_%7Breactants%7D%5C%5C%5CDelta%20H%5E%7Bo%7D_%7Brxn%7D%20%3D%20%5B2%5CDelta%20H%5E%7Bo%7D_%7Bf%7D%28CO_%7B2%7D%29%20%2B%20%5CDelta%20H%5E%7Bo%7D_%7Bf%7D%20%28H_%7B2%7DO%29%5D%20-%20%5B%5CDelta%20H%5E%7Bo%7D_%7Bf%7D%28C_%7B2%7DH_%7B2%7D%29%20%2B%20%5Cfrac%7B5%7D%7B2%7D%20%5CDelta%20H%5E%7Bo%7D_%7Bf%7D%20O_%7B2%7D%5D%5C%5C-1299.5%20%3D%202%28-393.5%29%20%2B%20%28-285.8%29%20-%20%5CDelta%20H%5E%7Bo%7D_%7Bf%7D%20%28C_%7B2%7DH_%7B2%7D%29%5C%5C%5CDelta%20H%5E%7Bo%7D_%7Bf%7D%20%28C_%7B2%7DH_%7B2%7D%29%20%3D%20227.7%20kJ%2Fmol)
Thus, we can conclude that heat of combustion per mole for acetylene is 227.7 kJ/mol.
