Answer:
The energy released as heat when 9.94 g Cu 2 O ( s ) undergo oxidation at constant pressure is -10.142 kJ
Explanation:
Here we have
2Cu₂O ( s ) + O₂ ( g ) ⟶ 4 CuO ( s ) Δ H ∘ rxn = − 292.0 kJ mol
In the above reaction, 2 Moles of Cu₂O (copper (I) oxide) react with one mole of O₂ to produce 4 moles of CuO, with the release of − 292.0 kJ/mol of energy
Therefore,
1 Moles of Cu₂O (copper (I) oxide) react with 0.5 mole of O₂ to produce 2 moles of CuO, with the release of − 146.0 kJ of energy
We have 9.94 g of Cu₂O with molar mass given as 143.09 g/mol
Hence the number of moles in 9.94 g of Cu₂O is given as
9.94/143.09 = 6.95 × 10⁻² moles of Cu₂O
6.95 × 10⁻² moles of Cu₂O will therefore produce 6.95 × 10⁻² × − 146.0 kJ mol or -10.142 kJ.
Answer:
B) ) –1615.1 kJ mol^–1
Explanation:
since
SiO2(s) + 4 HF(aq) → SiF4(g) + 2 H2O(l) ∆Hºrxn = 4.6 kJ mol–1
the enhalpy of reaction will be
∆Hºrxn = ∑νp*∆Hºfp - ∑νr*∆Hºfr
where ∆Hºrxn= enthalpy of reaction , ∆Hºfp= standard enthalpy of formation of products , ∆Hºfr = standard enthalpy of formation of reactants , νp=stoichiometric coffficient of products, νr=stoichiometric coffficient of reactants
therefore
∆Hºrxn = ∑νp*∆Hºfp - ∑νr*∆Hºfr
4.6 kJ/mol = [1*∆HºfX + 2*(–285.8 kJ/mol)] - [1*(–910.9kJ/mol) + 4*(–320.1 kJ/mol)]
4.6 kJ/mol =∆HºfX -571.6 kJ/mol + 2191.3 kJ/mol
∆HºfX = 4.6 kJ/mol + 571.6 kJ/mol - 2191.3 kJ/mol = -1615.1 kJ/mol
therefore ∆HºfX (unknown standard enthalpy of formation = standard enthalpy of formation of SiF4(g) ) = -1615.1 kJ/mol
Heat is being applied to the liquid. The right amount of heat causes the liquid to evaporate and become water vapor or steam-gas.
The chemical characteristics or reactivity of a chemical element is highly (mostly) dependent on the: number of valence electrons in its outermost shell.
<h3>What is
chemical characteristics?</h3>
A chemical characteristic can be defined as the properties of a chemical element or compound that is mainly observable and measurable during a chemical reaction such as reactivity.
<h3>What is a valence electron?</h3>
A valence electron can be defined as the number of electrons that are present in the outermost shell of an atom of a chemical element.
In Chemistry, the number of valence electrons (valency) is a property that is typically used to determine the chemical characteristics or reactivity of all chemical elements.
In conclusion, the chemical characteristics or reactivity of a chemical element is highly (mostly) dependent on the number of valence electrons in its outermost shell.
Read more on electrons here: brainly.com/question/377844
