Answer:
compound
Explanation:
When two distinct elements are chemically combined—i.e., chemical bonds form between their atoms—the result is called a chemical compound. Most elements on Earth bond with other elements to form chemical compounds, such as sodium (Na) and Chloride (Cl), which combine to form table salt (NaCl).
Answer:
A shell protects the bird
Explanation:
The answer is -60.57. With appropriate sig figs it becomes -60.6 KJ.
<span>I think you were on the right track. However you need to multiply H2O by its coefficient from the balanced equation. Then you also need to keep in mind the signs. </span>
<span>Maybe it's easier if I write what I did out: </span>
<span>2H2O > 2H2 +O2...............-H= 2* -285.83 </span>
<span>Ca + O2 + H2 > Ca(OH)2....H= -986.2 </span>
<span>2C + H2 > C2H2.................H= 226.77 </span>
<span>The above H's stand for standard enthalpy of formations. These can be found in textbook appendix. Notice the negative infront of the enthalpy (H) for H2O. This is to remind me/you that the heat lost is gained in the rxn. </span>
<span>So then you add them up. 226.77 - 986.2 + (2*285.83) = -187.77 </span>
<span>Add back the total enthalpy that is given in the question -187.77+127.2 = -60.57 </span>
<span>If signs cross you up find a way to remember that works for you. </span>
Answer:
(a) -134 kJ (b) -136 kJ
Explanation:
a) Using the accounting of the enthalpy of broken and formed bonds we will have the answer for this question ( remember the enthalpy of bonds broken are positive and those formed are negative)
ΔHrxn(kJ) = 6H (C-H) + 1 (C-C)+ 1H (H) + 1(C=C) + 4(C-H)
= 6(-411) +(-346) +432 + 602 + 4(411)
= - 134 kJ
(b) ΔHrxn = ΔHºf(C2H6) - ΔHºf (C2H4) = -83.75 kJ- 52.3 kJ = -136 kJ
( ΔHºf (H2)) = 0)
