Answer:
Mixture is a substance which has two or more components which do not combine chemically and do not have any fixed ratio in which they are present. Example: Air
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water
Air is a mixture of various gases , dust particles and water vapors which do not react chemically and thus the constituents retain their chemical properties. Water is a compound which is formed by chemical combination of hydrogen and oxygen which lose their individual chemical properties.
(AHC H20(I) = -285.8 kJ/mol)
A -120.9 kJ
B-241.8 kJ
C-571.6 kJ
D-285.8 kJ
Answer:
The heat of reaction when hydrogen and oxygen combine to form water is :
C. 571.6 kJ
Explanation:
Enthalpy Change = The enthalpy change for the formation of 1 mole of the substance from their standard state is called the enthalpy of formation.
This is intensive quantity as it is fixed for 1 mole .
Intensive properties = Those properties which are independent on the amount of the substance are intensive properties.
The value of these quantities does not get halve if you divide the substance into two equal parts. example , density, refractive index.
However , the enthalpy of reaction is extensive. Because on increasing the amount the value of the enthalpy also get doubles
Hence for this reaction :
Its value is -285.8 kJ for 1 mole
And here two moles are present . so the value of molar enthalpy is:
-285.8 x 2 = -571.6 kJ
The mass of the system consisting of the ice cube and the plastic cup will remain 5 grams even after the ice completely melts. This is because of the Conservation of Mass principle, which states that mass is not lost during a phase change.
The principle operating in this scenario is called the Conservation of Mass. In this specific context, this principle means that the mass of an object or a system of objects will remain the same regardless of the changes it may undergo, as long as no mass enters or leaves the system. In the case of an ice cube melting, although the physical state (phase) of the water changes from solid (ice) to liquid (water), its mass does not change.
So when an ice cube that weighs 5 grams (along with the cup) melts, it turns into an equivalent mass of liquid water. That means even after the ice has completely melted into water, the mass of the water and the plastic cup will still be 5 grams.
This is because during the phase change, only the state of the matter is altered (from solid to liquid), not its mass. The water molecules in the ice rearrange themselves and move apart during melting allowing the ice to become liquid water, but the number of molecules and thus the mass stays the same.
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B respiration
C pollination
D photosynthesis
Please help.