Answer:
The mole fraction of N₂ is 0.26.
Explanation:
The pressure exerted by a particular gas in a mixture is known as its partial pressure. So, Dalton's law states that the total pressure of a gas mixture is equal to the sum of the pressures that each gas would exert if it were alone:
PT = PA + PB
This relationship is due to the assumption that there are no attractive forces between the gases.
Dalton's partial pressure law can also be expressed in terms of the mole fraction of the gas in the mixture. The mole fraction is a dimensionless quantity that expresses the ratio of the number of moles of a component to the number of moles of all the components present.
So in a mixture of two or more gases, the partial pressure of gas A can be expressed as:
PA = XA * PT
In this case:
- PA= PN₂= 300 torr
- XA=XN₂= ?
- PT= 1.50 atm= 1140 torr (being 1 atm= 760 torr)
Replacing:
300 torr= XN₂*1140 torr
Solving:
XN₂= 0.26
<u><em>The mole fraction of N₂ is 0.26.</em></u>
Answer:
1. 6.005 g
2. 22.9 mL
3. Until the mixtures becomes homogeneous.
Explanation:
A buffer is a solution where a weak acid is in equilibrium with its conjugate base (its anion) or a weak base is in equilibrium with its conjugate base (its cation). The buffer remains the pH almost unaltered because it shifts the equilibrium if an acid or base is added.
1. The pH of a buffer can be calculated by the Henderson-Hasselbalch equation:
pH = pKa + log[A⁻]/[HA]
Where [A⁻] is the concentration of the conjugate base (the anion) of the acid, and HA is the acid concentration.
5.10 = 4.76 + log[A⁻]/[HA]
log[A⁻]/[HA] = 5.10 - 4.76
log[A⁻]/[HA] = 0.34
[A⁻]/[HA] = 
[A⁻]/[HA] = 2.1878
Because the volume is the same, we can replace the concentration by the number of moles (n):
nA⁻/nHA = 2.1878
nA⁻ = 2.1878*nHA
The total number of moles of the substances in the buffer is: 0.200 mol/L * 0.5 L = 0.1 mol
nA⁻ + nHA = 0.1
2.1878*nHA + n HA = 0.1
3.1878nHA = 0.1
nHA = 0.0314 mol
nA⁻ = 0.0686 mol
The total number of moles of acetic acid needed is 0.1 mol (both substances may be from it):
m = MW*mol
m = 60.05*0.1 = 6.005 g
2. NaOH must react with acetic acid to form the anion, so for a 1:1 reaction, it will be needed 0.0686 mol of NaOH:
V = mol/concentration
V = 0.0686/3
V = 0.0229 L = 22.9 mL
3. The buffer must be a homogeneous solution, it means that it can't be noticed phases in the buffer, so the flask must be inverted until all the buffer is diluted in water, and it will be noticed when the solution becomes homogenous.
Answer:
113 g NaCl
Explanation:
The Ideal Gas Law equation is:
PV = nRT
In this equation,
> P = pressure (atm)
> V = volume (L)
> n = number of moles
> R = 8.314 (constant)
> T = temperature (K)
The given values all have to due with the conditions fo F₂. You have been given values for all of the variables but moles F₂. Therefore, to find moles F₂, plug each of the values into the Ideal Gas Law equation and simplify.
(1.50 atm)(15.0 L) = n(8.314)(280. K)
2250 = n(2327.92)
0.967 moles F₂ = n
Using the Ideal Gas Law, we determined that the moles of F₂ is 0.967 moles. Now, to find the mass of NaCl that can react with F₂, you need to (1) convert moles F₂ to moles NaCl (via the mole-to-mole ratio using the reaction coefficients) and then (2) convert moles NaCl to grams NaCl (via molar mass from periodic table). It is important to arrange the ratios/conversions in a way that allows for the cancellation of units (the desired unit should be in the numerator).
1 F₂ + 2 NaCl ---> Cl₂ + 2NaF
Molar Mass (NaCl): 22.99 g/mol + 35.45 g/mol
Molar Mass (NaCl): 58.44 g/mol
0.967 moles F₂ 2 moles NaCl 58.44 g
---------------------- x ----------------------- x ----------------------- = 113 g NaCl
1 mole F₂ 1 mole NaCl
Answer:
Most radio waves have wavelengths between 1 mm and 100 km.
A cooling curve shows A. how the temperature of a substance falls as heat is removed.
Explanation:
<em>Radio waves</em> are the longest of all the waves in the electromagnetic spectrum.
Most have wavelengths between 1 mm and 100 km, although there is no upper limit.
Some radio waves have wavelengths of 10 000 km.
A <em>cooling curve</em> (see image below) shows how the temperature of a substance falls as it is cooled.
In Option E., a decrease in temperature would cause an energy <em>loss</em>.
Options B., C., and D. involve the <em>addition of heat</em>.
PbCr04 + P4O10
Hope this helps!
