Answer: 3.79
Explanation: The balanced chemical equation for the reaction between formic acid (HCOOH) and KOH is:
HCOOH + KOH → HCOOK + H2O
We can use the stoichiometry of this reaction to calculate the number of moles of formic acid that reacted with the KOH:
moles of KOH = (20.00 mL)(0.500 mol/L) = 0.01000 moles
moles of HCOOH = moles of KOH
Therefore, the initial number of moles of formic acid is:
moles of HCOOH = (10.00 mL)(x mol/L) = 0.01000 moles
where x is the molarity of formic acid.
Solving for x, we get:
x = 1.00 M
Therefore, the molarity of the formic acid is 1.00 M.
At the equivalence point, all of the formic acid has reacted with the KOH, and the solution contains only the salt formed by the reaction, potassium formate (HCOOK). The pH at the equivalence point can be calculated using the equation for the salt hydrolysis constant:
Kb = Kw/Ka
where Kb is the base dissociation constant of the conjugate base (formate ion), Kw is the ion product constant for water (1.0 × 10^-14 at 25°C), and Ka is the acid dissociation constant of the acid (formic acid). Rearranging this equation, we get:
Kb/Ka = [OH^-][HCOO^-]/[HCOOH]
At the equivalence point, the concentration of the formate ion (HCOO^-) is equal to the concentration of the KOH added (0.01000 moles / 30.00 mL = 0.3333 M). We can assume that the concentration of the hydroxide ion (OH^-) is also equal to 0.3333 M, since KOH is a strong base and will dissociate completely. Substituting these values into the equation above, we get:
Kb/Ka = (0.3333)^2 / [HCOOH]
Solving for [HCOOH], we get:
[HCOOH] = (0.3333)^2 / (1.8 × 10^-4) = 6181.5 M
Taking the negative logarithm of this concentration, we get the pH at the equivalence point:
pH = -log[HCOOH] = -log(6181.5) = 3.79
Therefore, the pH at the equivalence point is 3.79.
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Question
Which statement about fossil fuels is true?
Responses
They are an alternative energy source.
They are replaced in only a few years.
They are in high demand.
Answer:
They are in high demand.
Why is fossil fuel bad?
FOSSIL FUELS, USES, NEGATIVE IMPACTS AND SOLUTIONS;
In order to understand why it is bad to use Fossil Fuels, it is first necessary to understand what they are composed of. There are two main types of Fossil Fuels, namely, Coal and Oil.
The Formation of Coal : -
The multistage process that produces coal.
Many millennia ago, tree trunks fell and were quickly covered in water and mud. The bacteria, respiring anaerobically, due to the lack of Oxygen, produced peat. As is illustrated in stage 3, sediments built up over this peat layer and with time, heat and pressure, certain chemical changes turned the peat into Coal, as shown in stage 4. During the compression process, Sulphur compounds leached into the peat layer and eventually became a components of the final Coal. In other cases, Low sulfur coals derive their sulfur mainly from the sulfur components in the coal-forming plants. High-sulfur Coals, however, are now known to derive most of their sulfur from reduction of Sulphate ions to H2S in sea or brackish water in the coal beds by microbial processes.>
The Formation of Oil : -
The multistage process that produces oil.
Oil is essentially the remains of small fossilised sea creatures, that has been compressed and undergone pressures, eventually converted to oil. Oil is commonly accompanied by Natural Gas, which also builds up as a result of the extreme pressures. Sulphur is also found to make a percent of the oil.
The Usage and Combustion of Fossil Fuels : -
Coal and Oil are combusted to convert the chemical energy held to thermal energy, which in turn warms up water so that steam evolves. This team is drafted down a tunnel to turn a turbine, which drives a generator. This is how a power station works.
Upon observing the figure above, if you follow the path of the process, we see that coal enters at number 14 and enters the combuster at number 15. Here, it burns to heat the water at number 19, which is channeled down to drive the generator at number 5, via a series of tubes which converge into one, at number 10.
Coal or Oil or both can be used for this purpose. However the combustion of Coal and Oil releases Sulphur gas, which is dangerous for the Environment, as well as Carbon Dioxide and Carbon Monoxide, as the combustion happens in internal conditions, hence combustion may not occur fully, or in depleted Oxygen.
Negative Impacts of Sulphur Gas, Carbon Monoxide and Carbon Dioxide on the Atmosphere and the Environment : -
Sulphur Gas can dissolve in rainwater to produce a weak, aqueous Sulphuric Acid, which can fall in the form of rain. This can increase the pH of the soil or other water bodies, which can disturb marine ecosystems and even terrarial ones. It can fall on leafs and ‘wound’ them, i.e, destroy tissue due to its corrosive nature, making the plant life vulnerable to pathogens.Carbon Monoxide is a toxic gas that can cause suffocation and death. Although it is a natural component of the Atmosphere, in recent years, due to high industrial activity, its percent composition has increased significantly, which is a cause of concern towards the health of bird life. While it does not cause Greenhouse Effect directly, in the upper reaches of the Atmosphere it can combine with Oxygen to give Carbon Dioxide.…Which brings us to Carbon Dioxide. This is a greenhouse gas. On Earth, all organisms respire to produce Carbon Dioxide, so in the geological history of Earth, there has been equilibrium maintained between Oxygen and Carbon Dioxide in the Atmosphere. This, however, has been disturbed by Man’s industrial activities. This has been due to the high deforestation and lack of replacement of cut-down trees, around the planet. This disequilibrium is best depicted by the graph below.
Prevention and Reduction of These Effects : -
There are numerous methods by which these gases and their effects can be subdued. One notable example for the case of Sulphur Gas, is the “Flue Desulphurisation Method”, which effectively removes the Sulphur and separates it out, hence making it available for use in other Industrial Processes, but in safer compounds, etc.
Replanting of cut down trees can contribute towards of the re-achievement of the equilibrium that has been present in the Atmosphere before Industrial activities led to disequilibrium. Re-planting is a very simple process, but one that can go a long way. In effect, it is a two in one solution, as if we remove Carbon Monoxide emissions by reacting the gas with excess Oxygen, we get Carbon Dioxide. However, the equilibrium in the Biosphere means that is no longer a problem. Thus, replanting of trees is very important.
How many molecules of HCI are in 4.91 L of HCI acid at 25°C if the density equals 1.096 g/ml
To determine the number of HCl molecules in 4.91 L of HCl acid at 25°C, we can use the following steps:
Calculate the mass of the HCl acid in 4.91 L using its density.Convert the mass of HCl acid to the number of moles using its molar mass.Use Avogadro's number to convert the number of moles of HCl to the number of HCl molecules.Calculate the mass of the HCl acid in 4.91 L using its density:[tex]\qquad\sf {Density = \dfrac{mass}{volume}}[/tex]
[tex]\qquad\sf{mass = density \times volume}[/tex]
[tex]\qquad\sf{mass = 1.096 \: g/mL \times 4.91\: L = 5.38\: kg}[/tex]
Convert the mass of HCl acid to the number of moles using its molar mass. The molar mass of HCl is 36.46 g/mol.
[tex]\sf{moles = \dfrac{mass}{ molar\: mass} = \dfrac{5.38\: kg}{36.46\: g/mol} = 147.6\: mol}[/tex]
Use Avogadro's number to convert the number of moles of HCl to the number of HCl molecules. Avogadro's number is [tex]6.02 \times 10^23[/tex] molecules/mol.
[tex]\sf number\: of\: HCl\: molecules = moles \times Avogadro's\: number[/tex]
[tex]\begin{aligned}\sf number\: of\: HCl\: molecules& =\sf 147.6 \: mol \times 6.02 \times 10^23\: molecules/mol \\& =\sf 8.88 \times 10^25\: molecules\end{aligned}[/tex]
Therefore, there are [tex]8.88 \times 10^25[/tex] HCl molecules in 4.91 L of HCl acid at 25°C, assuming the density of the acid is 1.096 g/mL.
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