Answer:
Cabon-12 has same average atomic weight and mass number.
Explanation:
carbon-12 has average atomic weight 12 amu and mass number of 12.
amu represents average of mass of a nucleon.
As carbon-12 has same average atomic mass and mass number therefore carbon-12 is a good standard to determine average mass of a nucleon.
Again, abundance of carbon-12 isotope is almost equal to 99%. Therefore fluctuation of average atomic weight from 12 amu is very very low.
So, carbon-12 is taken as a standard to determine mass of a nucleon.
Hence atomic mass of carbon-12 is 12 amu.
Answer:
The heat produced is -15,1kJ
Explanation:
For the reaction:
2SO₂+O₂ → 2SO₃
The enthalpy of reaction is:
ΔHr = 2ΔHf SO₃ - 2ΔHf SO₂
As ΔHf SO₃ = -395,7kJ and ΔHf SO₂ = -296,8kJ
<em>ΔHr = -197,8kJ</em>
Using n=PV/RT, the moles of reaction are:
= <em>0,153 moles of reaction</em>
As 2 moles of reaction produce -197,8kJ of heat, 0,153moles produce:
0,153mol×
= <em>-15,1kJ</em>
<em></em>
I hope it helps!
A decrease in the amount of gas in a container will mean a decrease in pressure.
Answer:
C. As scientists have learned more about chemicals, they have become more aware of their dangers
Explanation:
Chemicals are substances with standard compositions, held together by chemical bonds. Chemicals can exist in different phases such as solid, liquid, and gaseous phases. Over time, with a growing understanding of chemicals, their composition, and their reaction methods, scientists now have a better knowledge of the dangers chemicals can pose. To that effect, they have created standard safety measures for those who have to work with these chemicals.
When these guidelines are strictly adhered to, the chances of suffering accidents, burns, and explosions with these chemicals are significantly reduced.
