<span>A device that generates an intense beam of coherent monochromatic light (or other electromagnetic radiation) by stimulated emission of photons from excited atoms or molecules. Lasers are used in drilling and cutting, alignment and guidance, and in surgery; the optical properties are exploited in holography, reading bar codes, and in recording and playing compact discs.</span>
The answer is -60.57 = -60.6 KJ.
CaC2(s) + 2 H2O(l) ---> Ca(OH)2(s) +C2H2(g) H= -127.2 KJ
Hf C2H2 = 226.77
Hf Ca(OH)2 = -986.2
<span>Hf H2O = -285.83
Now,
</span><span>add them up. 226.77 - 986.2 + (2*285.83) = -187.77
</span><span>Add back the total enthalpy that is given in the question
-187.77+127.2 = -60.57 </span>
Answer:
-100.125
Explanation:
We are given
CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (l) △H = -890.0 kJ/mol
The given information is for complete reaction
we have 1.8grams of Methane
Molar mass of CH4 = 16
No of moles of Methane = 1.8/ 16
= 0.1125
So the amount of the heat will be released from the amount of the methane
Q = No of moles*( -890.0 kJ/mol)
= 0.1125*(-890)
= -100.125kJ/mole
Therefore the amount of Energy released from 1.8 grams of methane is equal to -100.125
Answer:
1.385 × 10²³ atoms of calcium
Explanation:
Given data:
Number of moles of calcium = 0.23 mol
Number of atoms = ?
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
For 0.23 mole of calcium:
one mole = 6.022 × 10²³ atoms of calcium
0.23 × 6.022 × 10²³ atoms of calcium
1.385 × 10²³ atoms of calcium
