Ephedrine, a central nervous system stimulant, is used in nasal sprays as a decongestant. This compound is a weak organic base:
C10H15ON (aq) + H2O (l) -> C10H15ONH+ (aq) + OH- (aq)
A 0.035 M solution of ephedrine has a pH of 11.33.
a) What are the equilibrium concentrations of C10H15ON, C10H15ONH<span>+, and OH-</span>?
b) Calculate <span>Kb</span> for ephedrine.
c(C₁₀H₁₅NO) = 0,035 M.<span>
pH = 11,33.
pOH = 14 - 11,33 = 2,67.
[OH</span>⁻] =
10∧(-2,67) = 0,00213 M.<span>
[OH</span>⁻] =
[C₁₀H₁₅NOH⁺] = 0,00213 M.<span>
[</span>C₁₀H₁₅NO] = 0,035 M - 0,00213 M = 0,03287 M.<span>
Kb = [OH</span>⁻] ·
[C₁₀H₁₅NOH⁺] / [C₁₀H₁₅NO].<span>
Kb = (</span>0,00213 M)² / 0,03287 M = 1,38·10⁻⁴.
Phenolphthalein turn pink in basic solutions.it turn colourless in acid solution.
Hence options(1)is correct
Answer:
3.46x10⁴
Explanation:
Hello,
In this case, we can see that the number 34,560 has five significant figures, it means that if we want to write it with three, we must take the 3, 4 and 5 only. Nevertheless, since the 6 after the five is greater than 5, we can round such five to 6, so we obtain:
346
However, the decimal places cannot get lost, therefore, we move the given thousand to the three, so the number turns out:
3.46x10⁴
Best regards.
Answer:
1.327 g Ag₂CrO₄
Explanation:
The reaction that takes place is:
- 2AgNO₃(aq) + K₂CrO₄(aq) → Ag₂CrO₄(s) + 2KNO₃(aq)
First we need to <em>identify the limiting reactant</em>:
We have:
- 0.20 M * 50.0 mL = 10 mmol of AgNO₃
- 0.10 M * 40.0 mL = 4 mmol of K₂CrO₄
If 4 mmol of K₂CrO₄ were to react completely, it would require (4*2) 8 mmol of AgNO₃. There's more than 8 mmol of AgNO₃ so AgNO₃ is the excess reactant. <em><u>That makes K₂CrO₄ the limiting reactant</u></em>.
Now we <u>calculate the mass of Ag₂CrO₄ formed</u>, using the <em>limiting reactant</em>:
- 4 mmol K₂CrO₄ *
= 1326.92 mg Ag₂CrO₄
- 1326.92 mg / 1000 = 1.327 g Ag₂CrO₄
The data on Climate change is as explained below-
Explanation:
Climate change is the ominous “hard truth” concurrently. However, it is not the first time that climate change is happening. In geological history, we find plenty of evidence of climate change.
The most important and famous of all such changes is the climate change that occurred during the Mesozoic era leading to the extinction of Dinosaurus. The reason behind these all climate changes was different. However, the climate change we are witnessing at present has something extra to all this natural stuff.
The present climate change is fuelled by anthropogenic activities at large. Large scale emission of greenhouse gases possibly from burning of fossil fuels ever since the Industrial revolutions in the late 18th century has altered the chemical composition of atmospheric gases. In addition to the use of fossil fuels other activities such as agriculture, coal-based power plants, deforestation and other such activities have been instrumental in degrading the serene balance between different atmospheric gases.
The evidence of the present climate change can be gauged in-
- The rise in global average temperature-Earth’s mean temperature has risen by around 1° C ever since the 19th century. 2017 proved to be the warmest year in the record.
- Oceans have been net absorber of the heat. This has led to the warming up of oceans. This severely hampers and impact marine flora and fauna
- Deglaciation- the increasing temperature has manifested in the form of shrinking ice-sheets. Large icebergs are calving and thus has some serious long-term impact for the sustenance of mankind.
- Rise in the mean sea level- The sea level has risen by almost 10 inches since last century. This increase is all set to increase in future thus endangering the lives and livelihood of the coastal communities.
All the leading personalities of the time including the ex-president of the US Mr Barak Obama emphasised the importance of climate change and urged the global community to tackle it at earliest. In his words, he mentioned, “No other challenge poses as great a threat to the future generation as the climate change”. In addition to Mr Obama, noted climate activist Greta Thunberg described the climate change to be the greatest crisis to the humanity that it has ever faced.
Therefore, it can be safely argued that it’s urgent to talk and act tough on climate change. Climate change has transitioned into a multi-headed monster capable enough to devastate the entire mankind. It has done this earlier and sure to carry it further on.
