answer: -230kJ
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2. A rock occupies a volume of 20 cm and has a mass of 54 grams. Find the density of this rock.
1 answer:
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Answer:
1 ) Δs ( entropy change for hot block ) = - Q / th ( -ve shows heat lost to cold block )
Δs ( entropy change for cold block ) = Q / tc
∴ Total Δs = ΔSc + ΔSh
= Q/tc - Q/th
2) ΔSdecomposition = Δh / Temp = ( 181.6 * 10^3 / 773 ) = 234.928 J/k
Explanation:
<u>1) To show that heat flows spontaneously from high temperature to low temperature </u>
example :
Pick two(2) solid metal blocks with varying temperatures ( i.e. one solid block is hot and the other solid block is cold )
Place both blocks for time (t ) in an insulated system to reduce heat loss or gain to or from the environment
Check the temperature of both blocks after time ( t ) it will be observed that both blocks will have same temperature after time t ( first law of thermodynamics )
Δs ( entropy change for hot block ) = - Q / th ( -ve shows heat lost to cold block )
Δs ( entropy change for cold block ) = Q / tc
∴ Total Δs = ΔSc + ΔSh
= Q/tc - Q/th
<u>2) Entropy change for Decomposition of mercuric oxide </u>
2HgO (s) → 2Hg(l) + O₂ (g)
Δs = positive
there is transition from solid to liquid and the melting point of mercury ( the point at which reaction will take place ) = 500⁰C
hence ΔSdecomposition = S⁻ Hg - S⁻ HgO =
Δh of reaction = 181.6 KJ
Temp = 500 + 273 = 773 k
hence ΔSdecomposition = Δh / Temp = ( 181.6 * 10^3 / 773 ) = 234.928 J/k
Answer : The correct option is, (A)
Explanation :
Van't Hoff factor : It is defined as the ratio of the experimental value of the colligative property to the calculated value of the colligative property.
We can determine the van't Hoff factor by the association and dissociation of the compound.
(A)
It is an electrolyte that dissociates to give aluminum ion and chloride ion.
The dissociation of will be,
So, Van't Hoff factor = Number of solute particles = = 1 + 3 = 4
(B)
It is an electrolyte that dissociates to give potassium ion and iodide ion.
The dissociation of will be,
So, Van't Hoff factor = Number of solute particles = = 1 + 1 = 2
(C)
It is an electrolyte that dissociates to give calcium ion and chloride ion.
The dissociation of will be,
So, Van't Hoff factor = Number of solute particles = = 1 + 2 = 3
(D)
It is an electrolyte that dissociates to give magnesium ion and sulfate ion.
The dissociation of will be,
So, Van't Hoff factor = Number of solute particles = = 1 + 1 = 2
(E) Non-electrolyte
The dissociation non-electrolyte is not possible. So, the Van't Hoff factor will always be, 1.
Hence, the highest van't Hoff factor of solute is,
Hope this helps you.
Answer:
grams of sodium phosphate must be added to 1.4 L of this solution to completely eliminate the hard water ions
Explanation:
We will first write the balanced equation for this scenario
3 CaCl2 + 2 Na3PO4 ----> 6 NaCl + Ca3 (PO4)2
3 Mg(NO3)2 + 2 Na3PO4 -----> 6 NaNO3 + Mg3 (PO4)2
The ratio here for both calcium chloride and magnesium nitrate is
The number of moles of each compound is equal to
Using the mole ratio of 3:2, convert each to moles of sodium phosphate.
mole of CaCl2 is equal to
Na3PO4
mole of CaCl2 is equal to
Na3PO4
Converting moles of sodium phosphate to grams of sodium phosphate we get
g/mol
grams of sodium phosphate must be added to 1.4 L of this solution to completely eliminate the hard water ions