<span>Photons were the first sub-atomic particles detected, but not quite discovered as they could not be explained. Photons were first detected by Johann Wilhelm Ritter, Victor Schumann, and Winhelm Rontgen. The next, and first sub-atomic particle discovered, was the electron. The electron was discovered by J. J. Thompson in the late 1800s. The next two sub-atomic particle discoveries were the alpha particle and photon, discovered by Ernest Rutherford and Paul Villard respectively. Rutherford also discovered the proton and in 1932, James Chadwick discovered the neutron.</span>
Answer:
final concentration: Ca = 0.014 M
Explanation:
Velocity of reaction:
∴ α: order of reaction, assuming α = 1
∴ K = 0.249 s-1.......rate constant
∴ Cao = 0.050 M......initial concentration
∴ t = 5 s.......reaction time
⇒ δCa/δt = K*Ca
⇒ ∫δCa/Ca = K*∫δt
⇒ Ln(Cao/Ca) = K*t = (0.249s-1)(5 s) = 1.245
⇒ Cao/Ca = 3.473
⇒ Ca = 0.050/3.473
⇒ Ca = 0.014 M
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.
When dT = Kf * molality * i
= Kf*m*i
and when molality = (no of moles of solute) / Kg of solvent
= 2.5g /250g x 1 mol /85 g x1000g/kg
=0.1176 molal
and Kf for water = - 1.86 and dT = -0.255
by substitution
0.255 = 1.86* 0.1176 * i
∴ i = 1.166
when the degree of dissociation formula is: when n=2 and i = 1.166
a= i-1/n-1 = (1.166-1)/(2-1) = 0.359 by substitution by a and c(molality) in K formula
∴K = Ca^2/(1-a)
= (0.1176 * 0.359)^2 / (1-0.359)
= 2.8x10^-3
Ethylene- C2H4 = 85.7% Carbon and 14.3% Hydrogen
Find the atomic masses for each element and multiply it by the number of atoms in the compound, then add.
C- 12.0 * 2= 24.0
H- 1.00 * 4= 4.00
-----------------------
28.0
Take the masses for each element and divide it by the total mass. Then change the answer to get the percent.
C 24.0 / 28.0= .857 = 85.7%
H 4.00 / 28.0= .143 = 14.3%
<h3>
Ethylene is 85.7% Carbon and 14.3% Hydrogen </h3>
