Answer:
Acetic acid 0,055M and acetate 0,095M.
Explanation:
It is possible to prepare a 0,15M buffer of acetic acid/acetate at pH 5,0 using Henderson-Hasselblach formula, thus:
pH = pka + log₁₀ [A⁻]/[HA] <em>-Where A⁻ is acetate ion and HA is acetic acid-</em>
Replacing:
5,0 = 4,76 + log₁₀ [A⁻]/[HA]
<em>1,7378 = [A⁻]/[HA] </em><em>(1)</em>
As concentration of buffer is 0,15M, it is possible to write:
<em>[A⁻] + [HA] = 0,15M </em><em>(2)</em>
Replacing (1) in (2):
1,7378[HA] + [HA] = 0,15M
2,7378[HA] = 0,15M
[HA] = 0,055M
Thus, [A⁻] = 0,095M
That means you need <em>acetic acid 0,055M</em> and <em>acetate 0,095M</em> to obtain the buffer you need.
i hope it helps!
Answer:
It takes 1,068.76 grams of nitrogen to fill an 855 L tank at STP.
Explanation:
The STP conditions refer to the standard temperature and pressure. Pressure values at 1 atmosphere and temperature at 0 ° C or 273.15 °K are used and are reference values for gases.
On the other side, the pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:
P*V = n*R*T
where P is the gas pressure, V is the volume that occupies, T is its temperature, R is the ideal gas constant, and n is the number of moles of the gas.
So, in this case:
- P= 1 atm
- V= 855 L
- n= ?
- R= 0.082
- T= 273.15 K
Replacing:
1 atm* 855 L= n* 0.082 * 273.15 K
Solving:
n= 38.17 moles
Being the molar mass of nitrogen N2 equal to 28 g / mol, you can apply the following rule of three: if there are 28 grams in 1 mole, how much mass is there in 38.17 moles?
mass= 1,068.76 grams
<u><em>
It takes 1,068.76 grams of nitrogen to fill an 855 L tank at STP.</em></u>
Answer:
Explanation:
<u>Problem</u>:
In a gender based experiment, the blood pressure of different ages of men is been checked and recorded to determine if there is any correlation. What will be the independent, dependent and controlled variables?
<u>Answer</u>:
A controlled variable is the variable that is left constant throughout the course of an experiment. The controlled variable here is the gender.
A dependent variable is the variable that is been determined or measured during the course of an experiment. The dependent variable here is the blood pressure.
An independent variable is the variable that is intentionally or decidedly altered during the course of an experiment. The independent variable here is the age.
Explanation:
Characteristic of matter that is not associated with its change in chemical composition.
