Explanation:
When a brick is heated to a temperature between 20°C and 150°C, it loses most of the water added to the clay during the preparation phase. ... When the temperature starts to rise over 600°C, chemical changes begin to occur in the clay which give the brick colour, hardness and durability.
Answer:
78.3 × 10²³ atoms of helium are present in 52 g.
Explanation:
Given data:
Mass of He = 52 g
Number of atoms = ?
Solution:
First of all we will calculate the number of moles of He
Number of moles = mass /molar mass
Number of moles = 52 g/ 4 g/mol
Number of moles = 13 mol
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,
1 mole = 6.022 × 10²³ atoms of helium
13 mol × 6.022 × 10²³ atoms of helium / 1 mole
78.3 × 10²³ atoms of helium
Answer:
How do atoms give off light?
Atoms emit light when they are heated or excited at high energy levels. The color of light that is emitted by an atom depends on how much energy the electron releases as it moves down different energy levels. ... It shows the electron moving down energy levels.
Explanation:
Over 344.76 K the forward reaction will be spontaneous
<u><em>calculation</em></u>
ΔG = ΔH° -TΔs
if ΔG =0
therefore 0 =ΔH°-TΔs
ΔH° = TΔs
divide both side by Δs
T = ΔH°/Δs
convert 34.2 kj into j
that is 1 kj = 1000 j
34.2 kj =? j
<em>by cross multiplication</em>
=[34.2 kj x 1000j / 1 kj] = 34200 j
T is therefore = 34200 j÷99.2 j/k =344.76 k
if T is greater than 344.76 k the forward reaction will be spontaneous
