<span>It can be inferred from atomic line spectra. These are certain wavelengths of light that atoms give off when they become excited. The energy levels in an atom can be proven to exist from this phenomenon, and furthermore, they can be measured.</span>
<em>Answer:</em>
<em>Chemical properties:</em>
Those properties which change the chemical nature of matter.
<em>Example:</em>
- Heat of combustion
- Enthalpy of formation
<em>Physical properties:</em>
Those properties which do not change the chemical nature of matter.
<em>Example</em>
<em>Differences between chemical and physical properties:</em>
Chemical properties Physical properties
1. Observed after the change bringing 1. Observed with out being
the change change
2. These changes the molecules 2. only change physical state
3. Chemical identity changes 3.Chemical identity not changes
4. Structure of material changes 4.Structure of material not change
5. Chemical reaction is needed 5. No need of Chemical reaction
6. depend on composition 6. Does not depend on composition
Answer:
The system makes the transition from nonspontaneous to spontaneous at a temperature of 954.7 K.
Under 954.7 K the reaction is nonspontaneous; more than 954.7 K is the reaction spontaneous.
Explanation:
CH4(g) + 2H2O(g) ⇆ CO2(g) + 4H2(g)
CH4(g) H2O(g) CO2(g) H2(g) ΔH°f (kJ/mol): –74.87 –241.8 –393.5 0
ΔG°f (kJ/mol): –50.81 –228.6 –394.4 0
S°(J/K·mol): 186.1 188.8 213.7 130.7
ΔG<0 to be spontaneous
ΔG = ΔH- TΔS <0
ΔH = ∑nΔH(products) - ∑nΔH(reactant)
ΔH = (-393.5) - (–74.87 + 2*–241.8)
ΔH = 164.97 kJ = 164970 J
ΔS = ∑nΔS(products) - ∑nΔS(reactant)
ΔS = (213.7 + 4*130.7) - (186.1 + 2*188.8)
ΔS = 172.8 J
0 > 164970 J - T* 172.8 J
-164970 J > - T* 172.8 J
954.7< T
The system makes the transition from nonspontaneous to spontaneous at a temperature of 954.7 K.
Under 954.7 K the reaction is nonspontaneous; more than 954.7 K is the reaction spontaneous.
Make a ball of clay and embed small beads throughout it. The plum pudding model.
<span>The biogeochemical cycle that has the least activity because its essential element is mostly stored in rock is the phosphorus cycle. Phosphorus, unlike the other essential elements, is commonly found as a solid. This is why the atmosphere does not play a role in this cycle. Instead, phosphorus remains on land, and is mostly found in rocks and minerals.</span>