Indicators are substances that produce colour changes to indicate the presence or absence of a threshold concentration of a particular chemical specie. In neutralization reaction, indicators produce colour changes on the basis of the pH of the solution. In acid base titration, indicators are used to indicate the end point of the neutralization reaction. The end point of acid base titration is the equivalence point when the moles of the of the standard solution is equal to the moles of the unknown solution. Thus, the correct option is B. Note that the solution that contain the H+ ions is the acid.
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>
We have that the correct answer is the last one. NH4NO3 is called ammonium nitrate and is the salt that appears from combining HNO3 (acid) with NH3 (ammonia, base). We have then that a solution of this type is a buffer solution because ammonia is a weak base and the salt contains its conjugate acid (definition of buffer solution). The 2nd example is wrong because both potassium acetate and Acetic Acid are acids; no conjugate base is involved. HCI and NaCl are pairs of conjugacy (HCI is an acid and NACI can be produced by NaOH and HCI), but HCI is a strong acid and NACI is a salt. Hence, it cannot be a buffer solution (weak acid needed). Weak acid or base means that it does not fully break down in ions when in water.
The particle motion in a liquid is more spread apart, the particle motion in a solid is more compact together
Answer:
Explanation:
NaCl dissolves in water but not in benzene because the water-ion interactions are stronger than benzene-ion interactions.
This statement is true . NaCl is ionic compound . I water is ionises strongly because of strong ion - water interaction . It does not dissolve in benzene because of low ion - benzene interaction .
NaCl dissolves in water but not in hexane because the enthalpy of mixing NaCl with water is more negative than that of mixing NaCl with hexane.
This statement is wrong because enthalpy of mixing NaCl with water is positive and not negative .
NaCl dissolves in water but not in benzene(C6H6) because there are no hydrogen bonds in benzene.
This statement is wrong . NaCl does not make hydrogen bond with water molecule .
