Scientists are able to detect an El Niño<span> event and its effects on the climate through a variety of technological and natural sciences. One of these natural sciences is dendrochronology, or the study of tree rings. Dendrochronologists study the rings of a tree in order to understand climatic conditions during specific time periods. Thin rings often indicate drier seasons while fatter rings indicate rainy seasons. Depending on where the tree is, scientists can see past El </span>Niño<span> events in trees that exhibit signs of much rainier or drier seasons that normal.</span>
As defined by Arrhenius: An Arrhenius acid is a substance that dissociates in water to form hydrogen ions (H+). ... An Arrhenius base is a substance that dissociates in water to form hydroxide (OH–) ions. In other words, a base increases the concentration of OH– ions in an aqueous solution.
Answer:
HC2H3O2(I) + O2(g) ---> H2O(I) + CO2(g) ΔH= -72.35 kJ
Explanation:
We know that 5.0 g of acetic acid will contain, 5.0g/60 g/mol = 0.083 moles of acetic acid
Now from the reaction equation;
1 mole of acetic acid evolved -871.7 KJ of heat
0.083 moles of acetic acid will evolve 0.083 * -871.7 = -72.35 KJ
For 5.0 g of acetic acid, we can write;
HC2H3O2(I) + O2(g) ---> H2O(I) + CO2(g) ΔH= -72.35 kJ
Answer:
302 kj heat is released by lowering the temperature
Answer:
a)4.51
b) 9.96
Explanation:
Given:
NaOH = 0.112M
H2S03 = 0.112 M
V = 60 ml
H2S03 pKa1= 1.857
pKa2 = 7.172
a) to calculate pH at first equivalence point, we calculate the pH between pKa1 and pKa2 as it is in between.
Therefore, the half points will also be the middle point.
Solving, we have:
pH = (½)* pKa1 + pKa2
pH = (½) * (1.857 + 7.172)
= 4.51
Thus, pH at first equivalence point is 4.51
b) pH at second equivalence point:
We already know there is a presence of SO3-2, and it ionizes to form
SO3-2 + H2O <>HSO3- + OH-
![Kb = \frac{[ HSO3-][0H-]}{SO3-2}](https://tex.z-dn.net/?f=%20Kb%20%3D%20%5Cfrac%7B%5B%20HSO3-%5D%5B0H-%5D%7D%7BSO3-2%7D)

[HSO3-] = x = [OH-]
mmol of SO3-2 = MV
= 0.112 * 60 = 6.72
We need to find the V of NaOh,
V of NaOh = (2 * mmol)/M
= (2 * 6.72)/0.122
= 120ml
For total V in equivalence point, we have:
60ml + 120ml = 180ml
[S03-2] = 6.72/120
= 0.056 M
Substituting for values gotten in the equation ![Kb=\frac{[HSO3-][OH-]}{[SO3-2]}](https://tex.z-dn.net/?f=Kb%3D%5Cfrac%7B%5BHSO3-%5D%5BOH-%5D%7D%7B%5BSO3-2%5D%7D%20)
We noe have:

![x = [OH-] = 9.11*10^-^5](https://tex.z-dn.net/?f=x%20%3D%20%5BOH-%5D%20%3D%209.11%2A10%5E-%5E5)

=4.04
pH = 14- pOH
= 14 - 4.04
= 9.96
The pH at second equivalence point is 9.96