Answer:
Explanation:
The usefulness of a buffer is its ability to resist changes in pH when small quantities of base or acid are added to it. This ability is the consequence of having both the conjugate base and the weak acid present in solution which will consume the added base or acid.
This capacity is lost if the ratio of the concentration of conjugate base to the concentration of weak acid differ by an order of magnitude. Since buffers having ratios differing by more will have their pH driven by either the weak acid or its conjugate base .
From the Henderson-Hasselbach equation we have that
pH = pKa + log [A⁻]/[HA]
thus
0.1 ≤ [A⁻]/[HA] ≤ 10
Therefore the log of this range is -1 to 1, and the pH will have a useful range of within +/- 1 the pKa of the buffer.
Now we are equipped to answer our question:
pH range = 3.9 +/- 1 = 2.9 through 4.9
Answer:
2578.99 years
Explanation:
Given that:
100 g of the wood is emitting 1120 β-particles per minute
Also,
1 g of the wood is emitting 11.20 β-particles per minute
Given, Decay rate = 15.3 % per minute per gram
So,
Concentration left can be calculated as:-
C left = ![[A_t]=\frac{11.20\ per\ minute}{15.3\ per\ minute\ per\ gram}\times [A_0]= 0.7320[A_0]](https://tex.z-dn.net/?f=%5BA_t%5D%3D%5Cfrac%7B11.20%5C%20per%5C%20minute%7D%7B15.3%5C%20per%5C%20minute%5C%20per%5C%20gram%7D%5Ctimes%20%5BA_0%5D%3D%200.7320%5BA_0%5D)
Where,
![[A_t]](https://tex.z-dn.net/?f=%5BA_t%5D)
is the concentration at time t
![[A_0]](https://tex.z-dn.net/?f=%5BA_0%5D)
is the initial concentration
Also, Half life of carbon-14 = 5730 years
Where, k is rate constant
So,
The rate constant, k = 0.000120968 year⁻¹
Time =?
Using integrated rate law for first order kinetics as:
![[A_t]=[A_0]e^{-kt}](https://tex.z-dn.net/?f=%5BA_t%5D%3D%5BA_0%5De%5E%7B-kt%7D)
So,
![\frac {[A_t]}{[A_0]}=e^{-0.000120968\times t}](https://tex.z-dn.net/?f=%5Cfrac%20%7B%5BA_t%5D%7D%7B%5BA_0%5D%7D%3De%5E%7B-0.000120968%5Ctimes%20t%7D)
![\frac {0.7320[A_0]}{[A_0]}=e^{-0.000120968\times t}](https://tex.z-dn.net/?f=%5Cfrac%20%7B0.7320%5BA_0%5D%7D%7B%5BA_0%5D%7D%3De%5E%7B-0.000120968%5Ctimes%20t%7D)
<u>t = 2578.99 years</u>
A quantitative observation is not necessarily more useful than a non-quantitative one. However, quantitative observations do allow one to find trends.
(a), the sun rising is a non-quantitative observation.
(b), knowledge of the numerical relationship between the weight on the Moon and on Earth, is a quantitative observation.
(c), watching ice float on water does not involve a measurement; therefore, it must be a qualitative observation.
(d) the fact that we know that the water pump won’t work for depths more than 34 feet makes it quantitative. Again, seeing numbers is a giveaway that it’s a quantitative <span>observation. Quantitative is where you deal with numbers.</span>
It is both. It is a mixture because it has two or more things mixed in it. It is a solution, because all of the components and things mixed in the milk are uniform and milk isn't chunky or discolored because of that.
Hope this helps.
Answer:
Analytical Chemistry. The salt which in solution gives a pale green precipitate with sodium hydroxide solution and a white precipitate with barium chloride solution is : Iron (III) sulphate.
