Answer:
The rate of appearance of hydrogen gas is 0.095 M/s.
Explanation:
Rate of the reaction is the change in concentration of of any one of the reactants or products per unit time.
Given:
The rate of disappearance of HBr = ![-\frac{d[HBr]}{dt}=0.190 M/s](https://tex.z-dn.net/?f=-%5Cfrac%7Bd%5BHBr%5D%7D%7Bdt%7D%3D0.190%20M%2Fs)
Rate of the reaction is given by:
![R=-\frac{1}{2}\frac{d[HBr]}{dt}=\frac{1}{1}\frac{d[H_2]}{dt}](https://tex.z-dn.net/?f=R%3D-%5Cfrac%7B1%7D%7B2%7D%5Cfrac%7Bd%5BHBr%5D%7D%7Bdt%7D%3D%5Cfrac%7B1%7D%7B1%7D%5Cfrac%7Bd%5BH_2%5D%7D%7Bdt%7D)
![R=-\frac{1}{2}\frac{d[HBr]}{dt}=\frac{1}{2}\times 0.190 M/s=0.095 M/s](https://tex.z-dn.net/?f=R%3D-%5Cfrac%7B1%7D%7B2%7D%5Cfrac%7Bd%5BHBr%5D%7D%7Bdt%7D%3D%5Cfrac%7B1%7D%7B2%7D%5Ctimes%200.190%20M%2Fs%3D0.095%20M%2Fs)
Rate of appearance of the hydrogen gas:
![\frac{d[H_2]}{dt}=R =0.095 M/s](https://tex.z-dn.net/?f=%5Cfrac%7Bd%5BH_2%5D%7D%7Bdt%7D%3DR%20%3D0.095%20M%2Fs)
The rate of appearance of hydrogen gas is 0.095 M/s.
Given the wavelength of the yellow light (700 nm. in this case) we can find the frequency
<span>by dividing the speed of light c by the wavelength w, that is: f = c/w and we know that </span>
<span>c is equal to 2.998 * 10**8 meters per second. </span>
<span>So the frequency f = (2.998 * 10**8) / (7.0 * 10**-7) = 4.283 * 10**14 cycles per sec. </span>
<span>(or Hz.) Since the threshold frequency of Cs is 9.39 * 10**14 Hz, the red light doesn't </span>
<span>have a high enough frequency (or energy) to cause electron emission. </span>
<span>Hope this answers your question.</span>
Answer:
The amount of base needed is the amount that would give one mole of the hydroxide ion needed to neutralise one mole of the hydroxonium ion from the acid.
Explanation:
The chemical reaction between an acid and a base to form salt and water only is called a Neutralization reaction. Chemically
H⁺ + OH⁻ = H₂0
Hence, one mole of hydroxonium ion (H⁺) will combine with one mole of hydroxide ion (OH⁻) to give salt and water only.
In a completely neutralized reaction, the resulting salt is formed when there is complete dissociation of the acid and base to give salt and water with a pH of 7.
In the given question, the stated pH of between 8-9 tells us that the salt produced in this particular neutralization reaction is basic or alkaline. This usually occurs when a strong base reacts with a weak acid, producing a higher concentration of the hydroxide ion at equilibrium.
Hence the amount of base needed is the amount that would give one mole of the hydroxide ion needed to neutralise one mole of the hydroxonium ion from the acid.
If the concentration or molarity of the acid is known, then the exact amount of base required to neutralize it can be calculated. This is usually done via titrating the acid against drop wise solution of the base. Neutralization usually occurs when there is a change in colour of the resulting solution. The pH of the resulting solution can be determined using a litmus paper.
A blue litmus paper is indicative of a basic solution while a red litmus paper is indicative of an acidic solution.
