Answer:
These examples could be written as chemical reactions, but are more generally considered to be endothermic or heat-absorbing processes: Melting ice cubes. Melting solid salts. ... Converting frost to water vapor (melting, boiling, and evaporation, in general, are endothermic processes.
Explanation:
Answer:
A molecule can be defined as the combinations of two or more atoms are held together by chemical bonds. A molecule is the smallest portion of a substance which showcases all the properties of the substance.
Explanation:
Answer:
0.5 moles
Explanation:
Given data:
Number of moles of N₂O₄ = ?
Number of molecules = 3.011 × 10²³ molecules
Solution:
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
For example,
18 g of water = 1 mole = 6.022 × 10²³ molecules of water
1.008 g of hydrogen = 1 mole = 6.022 × 10²³ atoms of hydrogen
Number of moles in 3.011 × 10²³ molecules of N₂O₄.
3.011 × 10²³ molecules × 1 mol / 6.022 × 10²³ molecules
0.5 moles
Answer:
The answer is b), -228 kJ
Explanation:
First, we consider which bonds are broken and formed during the reaction
Broken, Br - Br (02 molecules), C ≡ C
Formed, C - C, C - Br (4 bonds)
Noted that when breaking bonds, the molecules NEED energy, while forming bond, they release energy. So, secondly, we calculate
Breaking energy = 2 x (Br-Br) + 1 x (C≡C) = 2 x 193 + 1 x 837 = 1,223 kJ
Forming energy = - (4 x (C-Br) + 1 x (C-C) = - (4 x 276 + 1 x 347) = - 1,451 kJ (minus means that the energy is released during the reaction)
Hence the ΔH°ᵣₓₙ is 1,223 kJ + (-1,451) kJ = - 228 kJ
From the reaction you can state the molar ratios:
3 mol A : 5 mol B : 1 mol C : 2 mol D : 1 mol E.
Given that B and C are in excess, you know that reactant A is the limiting reactant, which means that is reacts completely. So, you can use the number of moles of reactant B to find how many moles of the products are produced.
For that, you build a proportion with the molar ratios between A and E, and the number of moles of A that reacted:
=> 3 mol A / 1 mol E = 6 mol A / x => x = 6 mol A * 1 mol E / 3 mol A
=> x = 6*1/3 mol E = 2 mol E.
Answer: 2 moles of E.
