Weak base: [OH⁻] = √Kb.C
pKb = 4.2
c = concentration
MM Amphetamine (C9H13N) = 135.21 g/mol
c = 215 mg/L = (0.215 g : 135,21 g/mol) / L = 0.00159 mol/L = 1.59 x 10⁻³ mol/L
![\tt [OH^-]=\sqrt{10^{-4.2}\times 1.59\times 10^{-3}}=3.17\times 10^{-4}](https://tex.z-dn.net/?f=%5Ctt%20%5BOH%5E-%5D%3D%5Csqrt%7B10%5E%7B-4.2%7D%5Ctimes%201.59%5Ctimes%2010%5E%7B-3%7D%7D%3D3.17%5Ctimes%2010%5E%7B-4%7D)
pOH = 4 - log 3.17
pH = 14 - (4 - log 3.17)
pH = 10 + log 3.17 = 10.50
Answer:
Metallic bonding
Explanation:
Metals have low ionization energies. Therefore, their valence electrons are easily delocalized (attracted to the neighbouring metal atoms). These delocalized electrons are then not associated with a specific metal atom. Since the electrons are “free”, the metal atoms have become cations, and the electrons are free to move throughout the whole crystalline structure.
We say that a metal consists of an array of cations immersed in a sea of electrons
.
The electrons act as a “glue” holding the cations together.
Metallic bonds are the attractive forces between the metal cations and the sea of electrons.
In an NaK alloy, for example, the Na and K atoms contribute their valence electrons to the "sea". The atoms aren’t bonded to each other, but they are held in place by the metallic bonding.
Answer:
Cooking with open, exposed flame to prevent build up of CO₂ which will extinguish the fire
Explanation:
In the cooking process whereby food is heated by the combustion of cooking gas as follows;
C₄H₁₀ (g) + (13/2)O₂ → 4CO₂(g) + 5H₂O(g), ΔH = -2658 kJ·mol⁻¹
The product of the combustion must be allowed to escape freely to allow for more reactant molecules of oxygen and butane to effectively combine.
Whereby, the CO₂ is allowed to remain and accumulate at the reaction site, the CO₂ displaces the oxygen and reduces the butane such that as the CO₂ builds up without removal, the CO₂ and butane will left in the mixture while the fire is extinguished.
Answer:
The answers to the questions are as follows
- The temperature of the water bath goes up
- The piston moves out
- Heat flows out of the gaseous mixture
- 173.kJ flows out of the system
Explanation:
- From the question, it is noted that 173.kJ of heat flows out of the system into the insulated water bath therefore the temperature of the water bath goes up
as seen in the relation ΔH = m·c·ΔT
Where ΔH heat measured by temperature rise ΔT of a given mass of water m of specific heat capacity of 4.2 J/g°C
- The amount of heat measured from previous experiment is more than the heat from the present reaction therefore since in the present reaction is constant pressure and from the first law of thermodynamics Energy can neither be created nor destroyed, the balance heat will be transformed to work evidence in the piston moving out
ΣH = Q + W where
w = P × ΔV = P × (P₂ - P₂)
- Heat flows out of the gaseous mixture and is sensed from the rise in the temperature of the water bath
- 173.kJ flows out of the system
Answer:
the answer is b.CH3NO2 I guess I'm correct
