Answer:
By using any one technique like boiling, distillation, condensation ,etc , one can be used to distinguish between a pure substance and a homogeneous mixture.
Explanation:
If the liquid is a pure substance, then it can not be separated by using physical means because all atoms of a pure substance show same properties.
But on the other hand, if there is homogeneous mixture, it can be separated by using techniques like boiling, distillation, condensation ,etc.
<u>Thus, using any of the one method listed above can be used to distinguish between a pure substance and a homogeneous mixture.</u>
If element X has 59 protons then element X has 59 electrons.
Side note: as long as an element stays an atom the number of protons and electrons will always have the same value.
Answer:
As the axial tilt increases, then the seasonal contrast increases so that winters are colder and summers are warmer in both hemispheres. The northern hemisphere is tipped away from the Sun, producing short days and a low sun angle. What kind of effect does the earth's tilt and subsequent seasons have on our length of daylight (defined as sunrise to sunset). Over the equator, the answer is not much.
As for #5, it's mixed at the end of my answer, but just remember the spring equinox marks the change from 24 hours of darkness to 24 hours of daylight at Earth's poles .
Answer:
ΔH = - 272 kJ
Explanation:
We are going to use the fact that Hess law allows us to calculate the enthalpy change of a reaction no matter if the reaction takes place in one step or in several steps. To do this problem we wll add two times the first step to second step as follows:
N2(g) + 3H2(g) → 2NH3(g) ΔH=−92.kJ Multiplying by 2:
2N2(g) + 6H2(g) → 4NH3(g) ΔH=− 184 kK
plus
4NH3(g) + 5O2(g) → 4NO(g) +6H2O(g) ΔH=−905.kJ
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2N2(g) + 6H2(g) + 5O2(g)→ 4NO(g) + 6H2O(g) ΔH = (-184 +(-905 )) kJ
ΔH = -1089 kJ
Notice how the intermediate NH3 cancels out.
As we can see this equation is for the formation of 4 mol NO, and we are asked to calculate the ΔH for the formation of one mol NO:
-1089 kJ/4 mol NO x 1 mol NO = -272 kJ (rounded to nearest kJ)
