Answer:
The atomic radius of strontium is larger than magnesium because there are more number of shielding electrones in strontium than magnesium, which causes electron-electron repulsion, that makes the electrons in valance shell to expand. Hence it would decrease the effective nuclear charge.
Average atomic mass of an element=Atomic mass isotope₁* percent abundance isotope₁ + Atomic mass isotope₂* percent abundance isotope₂+<span>Atomic mass isotope</span>₃<span>* percent abundance isotope</span>₃....
average atomic mass=39.96 u*0.9959+37.96 u*0.00065+
35.97 u*0.00366≈39.95 u
Answer: the average atomic mass of this element is 39.95 u
Answer:
The property of water which makes it to attach or stick to another surface is Adhesion.
Explanation:
Adhesion is the characteristic ability a substance possess to stick to other substances. This is as a result of the covalent bond existing between the two hydrogen atoms and the one oxygen atom in the water molecule.
An example of the property of Adhesion is a water drop that stuck to the end of the pine needles
Answer:
-1.75
Explanation:
Given
Mass of acid = 10.14g
Mass of water = 511g
Molar mass of the acid = 93.0g/mol
Freezing point = -0.368°C
To get the molality of the solution
Molality = (Number of moles of solute ×1000) / Mass of solvent (g)
Molality = (Mass of solute × 1000) / Molar mass of solute × Mass of solvent (g)
Molality = (10.14g × 1000) /(93.0g/mol × 511g)
= 0.21m
Vant Hoff factor (Ka) is used to calculate the extent of dissociation and it is given by the equation T = i×m×Kf
Where T is change in freezing point of the solution
i is Vant Hoff factor
m is the molality of the solute
Kf is the cryoscopic constant. For water Kf is taken as 1
Therefore
-0.368°C = i × 0.21m × 1
i= -0.368/0.21
= -1.75
Answer:
ΔH°c = - 1605.1 KJ
Explanation:
- CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
∴ ΔHf CH4(g) = - 74.6 KJ/mol
∴ ΔHf CO2(g) = - 393.5bKJ/mol
∴ ΔHfH2O(g) = - 241.82 KJ/mol
standard enthalpy of combustion (ΔH°c):
⇒ ΔH°c = (2)(ΔHf H2O) + ΔHfCO2 - ΔHfCH4
⇒ ΔH°c = (2)(- 241.82) + ( - 393.5 ) - ( - 74.6 )
⇒ ΔH°c = - 802.54 KJ/mol
⇒ ΔH°c = ( - 802.54 KJ/mol )( 2 mol CH4 )
⇒ ΔH°c = - 1605.08 KJ