Answer:
The reaction is exothermic (option 4)
Explanation:
P4 + 5O2 → P4O10 + 712 kcal
In chemical reactions heat can be absorbed or released:
⇒in the first case, when heat is absorbed, this is called an endothermic reaction. The products have more energy than the reactants. The reaction requires or absorbs energy from it's surroundings. That means that in this reaction energy , in the form of heat, will be absorbed by the reactants.
⇒ when heat is released, this is called an exothermic reaction. The reactants have more energy than the products. The reaction gives or releases energy to it's surroundings. That means that in this reaction energy , in the form of heat, will be released by the reactants.
in the case of P4 + 5O2 → P4O10 + 712 kcal
We notice that on the right side, which is the product side, there is a positive amount of energy. This means that the energy is released by the the reactants, in this reaction. <u>The reaction is exothermic.</u>
.
The mass of hydrazine (N₂H₄) required to produce 96 g of water (H₂O) is 85.4 g (Option C)
<h3>Balanced equation </h3>
N₂H₄ + O₂ —> N₂ + 2H₂O
Molar mass of N₂H₄ = (2×14) + (4×1) = 32 g/mol
Mass of N₂H₄ from the balanced equation = 1 × 32 = 32 g
Molar mass of H₂O = (2×1) + 16 = 18 g/mol
Mass of H₂O from the balanced equation = 2 × 18 = 36 g
SUMMARY
From the balanced equation above,
36 g of H₂O were produced by 32 g of N₂H₄
<h3>How to determine the mass of N₂H₄</h3>
From the balanced equation above,
36 g of H₂O were produced by 32 g of N₂H₄
Therefore,
96 g of H₂O will be produced by = (96 × 32) / 36 = 85.4 g of N₂H₄
Thus, 85.4 g of N₂H₄ is needed for the reaction
Learn more about stoichiometry:
brainly.com/question/14735801
Hey there!
Ca + H₃PO₄ → Ca₃(PO₄)₂ + H₂
Balance PO₄.
1 on the left, 2 on the right. Add a coefficient of 2 in front of H₃PO₄.
Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + H₂
Balance H.
6 on the left, 2 on the right. Add a coefficient of 3 in front of H₂.
Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + 3H₂
Balance Ca.
1 on the right, 3 on the right. Add a coefficient of 3 in front of Ca.
3Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + 3H₂
Our final balanced equation:
3Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + 3H₂
Hope this helps!
The given question is incomplete. The complete question is:What is the relative atomic mass of a hypothetical element that consists isotopes in the indicated natural abundances.
Isotope mass amu Relative abundance
1 77.9 14.4
2 81.9 14.3
3 85.9 71.3
Express your answer to three significant figures and include the appropriate units.
Answer: 84.2 amu
Explanation:
Mass of isotope 1 = 77.9
% abundance of isotope 1 = 14.4% = 
Mass of isotope 2 = 81.9
% abundance of isotope 2 = 14.3% = 
Mass of isotope 3 = 85.9
% abundance of isotope 2 = 71.3% = 
Formula used for average atomic mass of an element :

![A=\sum[(77.9\times 0.144)+(81.9\times 0.143)+(85.9\times 0.713)]](https://tex.z-dn.net/?f=A%3D%5Csum%5B%2877.9%5Ctimes%200.144%29%2B%2881.9%5Ctimes%200.143%29%2B%2885.9%5Ctimes%200.713%29%5D)

Therefore, the average atomic mass of a hypothetical element that consists isotopes in the indicated natural abundances is 84.2 amu