Answer:
Only one—(i), or (ii), or (iii)—increases the reaction rate.
Explanation:
<em>Which of the following changes always leads to an increase in the rate constant for a reaction?</em>
- <em>Decreasing the temperature. </em>NO. A lower temperature leads to a slower reaction because the molecules have less energy to react.
- <em>Decreasing the activation energy</em>. YES. According to the Arrhenius equation, the lower the activation energy, the higher the rate constant.
- <em>Making the value of ΔE more negative</em>. NO. A more negative ΔE means a reaction is more spontaneous but not faster.
There are many kinds of pyroclastic material ejected during a volcanic eruption. Ash is the most common pyroclastic rock material ejected during an eruption. Volcanic ash is so fine that it can be blown into the atmosphere and picked up by the jet stream where it can circle the Earth for several years.
Answer:K2X
Explanation: Valency can be defined as the combining power of an element. It is the valency that dictates the value an element will have when writing a chemical formula for its compound.
MgX is a compound of magnesium and an element X. The valency of magnesium in most of its compound is +2. Now for the 2 to have been absent in the chemical formula, this shows that the element X itself have a valency if -2 for the valencies of both to have canceled out.
Now considering the element potassium, it is an alkaline metal belonging to group 1 of the periodic table. Hence, it is expected that it has a valency of +1
Forming a compound with element X means there would be an exchange of valencies between the two. We have established that x has a valency of -2. The formula of the compound thus formed by exchanging the valencies of both element would be K2X
<u>Answer:</u> The concentration of
required will be 0.285 M.
<u>Explanation:</u>
To calculate the molarity of
, we use the equation:

Moles of
= 0.016 moles
Volume of solution = 1 L
Putting values in above equation, we get:

For the given chemical equations:

![Ni^{2+}(aq.)+6NH_3(aq.)\rightleftharpoons [Ni(NH_3)_6]^{2+}+C_2O_4^{2-}(aq.);K_f=1.2\times 10^9](https://tex.z-dn.net/?f=Ni%5E%7B2%2B%7D%28aq.%29%2B6NH_3%28aq.%29%5Crightleftharpoons%20%5BNi%28NH_3%29_6%5D%5E%7B2%2B%7D%2BC_2O_4%5E%7B2-%7D%28aq.%29%3BK_f%3D1.2%5Ctimes%2010%5E9)
Net equation: ![NiC_2O_4(s)+6NH_3(aq.)\rightleftharpoons [Ni(NH_3)_6]^{2+}+C_2O_4^{2-}(aq.);K=?](https://tex.z-dn.net/?f=NiC_2O_4%28s%29%2B6NH_3%28aq.%29%5Crightleftharpoons%20%5BNi%28NH_3%29_6%5D%5E%7B2%2B%7D%2BC_2O_4%5E%7B2-%7D%28aq.%29%3BK%3D%3F)
To calculate the equilibrium constant, K for above equation, we get:

The expression for equilibrium constant of above equation is:
![K=\frac{[C_2O_4^{2-}][[Ni(NH_3)_6]^{2+}]}{[NiC_2O_4][NH_3]^6}](https://tex.z-dn.net/?f=K%3D%5Cfrac%7B%5BC_2O_4%5E%7B2-%7D%5D%5B%5BNi%28NH_3%29_6%5D%5E%7B2%2B%7D%5D%7D%7B%5BNiC_2O_4%5D%5BNH_3%5D%5E6%7D)
As,
is a solid, so its activity is taken as 1 and so for 
We are given:
![[[Ni(NH_3)_6]^{2+}]=0.016M](https://tex.z-dn.net/?f=%5B%5BNi%28NH_3%29_6%5D%5E%7B2%2B%7D%5D%3D0.016M)
Putting values in above equations, we get:
![0.48=\frac{0.016}{[NH_3]^6}}](https://tex.z-dn.net/?f=0.48%3D%5Cfrac%7B0.016%7D%7B%5BNH_3%5D%5E6%7D%7D)
![[NH_3]=0.285M](https://tex.z-dn.net/?f=%5BNH_3%5D%3D0.285M)
Hence, the concentration of
required will be 0.285 M.
The first step to answering this item is to convert the given temperatures in °F to °C through the equation,
°C = (°F - 32)(5/9)
initial temperature: 72°F
°C = (72 - 32)(5/9) = 22.22°C
final temperature: 145°F
°C = (145 - 32)(5/9) = 62.78°C
Substituting to the equation,
H = mcpdT
H = (43 g)(0.903 J/g°C)(62.78 - 22.22)
H = 1574.82 J
<em>Answer: 1574.82 J</em>