Answer:
e. When the indicator changes color and remains, 2 more drops of the solution in the buret should be added.
Explanation:
<em>Which statement is incorrect?
</em>
<em>Select one:
</em>
<em>
a. The volume of solution in the buret should be recorded when the endpoint is reached.
</em> CORRECT. At the endpoint, the titrant is expected to have completely reacted with the titrand.
<em>b. It is good practice to place the flask over a white background to better observe the color change of the solution.</em> CORRECT. Using a white background makes it easier to detect the changes in the color of the indicator.
<em>c. The endpoint is when the indicator changes color.</em>
CORRECT. This is the function of an indicator.
<em>d. Phenolphthalein will go from a colorless solution to a pink solution for the addition of NaOH to an acid solution.</em> CORRECT. Phenolphthalein is colorless when pH < 8.3 and it is pink when pH > 10.0.
<em>e. When the indicator changes color and remains, 2 more drops of the solution in the buret should be added.</em> INCORRECT. When the endpoint is reached, no more titrant should be added.
<span>Several
important pollutants are produced by fossil fuel combustion: carbon
monoxide, nitrogen oxides, sulfur oxides, and hydrocarbons. In addition,
total suspended particulates contribute to air pollution, and nitrogen
oxides and hydrocarbons can combine in the atmosphere to form
tropospheric ozone, the major constituent of smog.
Carbon monoxide is a gas formed as a by-product during the incomplete
combustion of all fossil fuels. Exposure to carbon monoxide can cause
headaches and place additional stress on people with heart disease. Cars
and trucks are the primary source of carbon monoxide emissions.
Two oxides of nitrogen--nitrogen dioxide and nitric oxide--are formed in
combustion. Nitrogen oxides appear as yellowish-brown clouds over many
city skylines. They can irritate the lungs, cause bronchitis and
pneumonia, and decrease resistance to respiratory infections. They also
lead to the formation of smog. The transportation sector is responsible
for close to half of the US emissions of nitrogen oxides; power plants
produce most of the rest.
Sulfur oxides are produced by the oxidization of the available sulfur in
a fuel. Utilities that use coal to generate electricity produce
two-thirds of the nation's sulfur dioxide emissions. Nitrogen oxides and
sulfur oxides are important constituents of acid rain. These gases
combine with water vapor in clouds to form sulfuric and nitric acids,
which become part of rain and snow. As the acids accumulate, lakes and
rivers become too acidic for plant and animal life. Acid rain also
affects crops and buildings.
Hydrocarbons are a broad class of pollutants made up of hundreds of
specific compounds containing carbon and hydrogen. The simplest
hydrocarbon, methane, does not readily react with nitrogen oxides to
form smog, but most other hydrocarbons do. Hydrocarbons are emitted from
human-made sources such as auto and truck exhaust, evaporation of
gasoline and solvents, and petroleum refining.
The white haze that can be seen over many cities is tropospheric ozone,
or smog. This gas is not emitted directly into the air; rather, it is
formed when ozone precursors mainly nonmethane hydrocarbons and nitrogen
oxides react in the presence of heat and sunlight. Human exposure to
ozone can produce shortness of breath and, over time, permanent lung
damage. Research shows that ozone may be harmful at levels even lower
than the current federal air standard. In addition, it can reduce crop
yields.
Finally, fossil fuel use also produces particulates, including dust,
soot, smoke, and other suspended matter, which are respiratory
irritants. In addition, particulates may contribute to acid rain
formation.
Also, water and land pollution.
</span>
MW of gas : 124.12 g/mol
<h3>Further explanation </h3>
Density is a quantity derived from the mass and volume
Density is the ratio of mass per unit volume
With the same mass, the volume of objects that have a high density will be smaller than objects with a smaller type of density
The unit of density can be expressed in g/cm³ or kg/m³
Density formula:
ρ = density
m = mass
v = volume
glass vessel wieight = 50 g
glass vessel + liquid = 148 ⇒ liquid = 148 - 50 =98 g
volume of glass vessel :
An ideal gas :
m = 50.5 - 50 = 0.5 g
P = 760 mmHg = 1 atm
T = 300 K
Molarity is expressed as
the number of moles of solute per volume of the solution. The mass of oxalic acid dihydrate needed for the solution is calculated as follows:
Amount in moles: (0.357 mol H2C2O4•2H2O / L) (.250 L ) = 0.0893 mol H2C2O4•2H2O
Amount in mass : 0.0893 mol H2C2O4•2H2O (126.08 g / mol ) = 11.2589 g H2C2O4•2H2O
Hope this answers the question. Have a nice day.
Answer:
V₂ = 21.3 dm³
Explanation:
Given data:
Initial volume of gas = 3.00 dm³
Initial pressure = 101 Kpa
Final pressure = 14.2 Kpa
Final volume = ?
Solution;
The given problem will be solved through the Boly's law,
"The volume of given amount of gas is inversely proportional to its pressure by keeping the temperature and number of moles constant"
Mathematical expression:
P₁V₁ = P₂V₂
P₁ = Initial pressure
V₁ = initial volume
P₂ = final pressure
V₂ = final volume
Now we will put the values in formula,
P₁V₁ = P₂V₂
101 Kpa × 3.00 dm³ = 14.2 Kpa × V₂
V₂ = 303 Kpa. dm³/ 14.2 Kpa
V₂ = 21.3 dm³
Explanation:
