Answer:
A) Ca(s) + C(s) + 3/2 O₂(g) → CaCO₃(s)
Explanation:
Standard enthalpy of formation of a chemical is defined as the change in enthalpy durin the formation of 1 mole of the substance from its constituent elements in their standard states.
The consituent elements of calcium carbonate, CaCO₃, in their standard states (States you will find this pure elements in nature), are:
Ca(s), C(s) and O₂(g)
That means, the equation that represents standard enthalpy of CaCO₃ is:
<h3>A) Ca(s) + C(s) + 3/2 O₂(g) → CaCO₃(s)</h3><h3 />
<em>Is the equation that has ΔH° = -1207kJ/mol</em>
Answer:
#Molecules XeF₆ = 2.75 x 10²³ molecules XeF₆.
Explanation:
Given … Excess Xe + 12.9L F₂ @298K & 2.6Atm => ? molecules XeF₆
1. Convert 12.9L 298K & 2.6Atm to STP conditions so 22.4L/mole can be used to determine moles of F₂ used.
=> V(F₂ @ STP) = 12.6L(273K/298K)(2.6Atm/1.0Atm) = 30.7L F₂ @ STP
2. Calculate moles of F₂ used
=> moles F₂ = 30.7L/22.4L/mole = 1.372 mole F₂ used
3. Calculate moles of XeF₆ produced from reaction ratios …
Xe + 3F₂ => XeF₆ => moles of XeF₆ = ⅓(moles F₂) = ⅓(1.372) moles XeF₆ = 0.4572 mole XeF₆
4. Calculate number molecules XeF₆ by multiplying by Avogadro’s Number (6.02 x 10²³ molecules/mole)
=> #Molecules XeF₆ = 0.4572mole(6.02 x 10²³ molecules/mole)
= 2.75 x 10²³ molecules XeF₆.
Answer:
<em>a)</em> <em>1.392 x 10^6 g/cm^3</em>
<em>b) 8.69 x 10^7 lb/ft^3</em>
<em></em>
Explanation:
mass of the star m = 2.0 x 10^36 kg
radius of the star (assumed to be spherical) r = 7.0 x 10^5 km = 7.0 x 10^8 m
The density of substance ρ = mass/volume
The volume of the star = volume of a sphere = 
==> V = 
= 1.437 x 10^27 m^3
density of the star ρ = (2.0 x 10^36)/(1.437 x 10^27) = 1.392 x 10^9 kg/m^3
in g/cm^3 = (1.392 x 10^9)/1000 = <em>1.392 x 10^6 g/cm^3</em>
in lb/ft^3 = (1.392 x 10^9)/16.018 = <em>8.69 x 10^7 lb/ft^3</em>
Just choose 3
1) Lakes can form in hollows left by meteorite impacts (e.g. Clearwater Lakes, Quebec, Canada).
2) Lakes can form in the craters formed by volcanoes (e.g. Crater Lake, Oragon)
3) Lakes can form when a river is damed by a natural rock fall or man (e.g. Lake Mede)
4) Lakes can form where glaciers have scooped out the rock from the floor of a valley (e.g. Lake Geneva)
5) Lakes can form where block faulting lowers the land (e.g. lake Baikal)
6) lakes can form in natural depressions in the land (e.g. Lake Victoria)
<u>Answer:</u> The correct answer is Option c.
<u>Explanation:</u>
Vaporization is defined as the physical process in which liquid particles get converted to gaseous particles.
The value of standard Gibbs free energy is 0 for equilibrium reactions.
To calculate 
for the reaction, we use the equation:
where,
= standard entropy change of vaporization
= standard enthalpy change of vaporization = 30.7 kJ/mol = 30700 J/mol (Conversion factor: 1 kJ = 1000 J)
T = temperature of the reaction = 353.3 K
Putting values in above equation, we get:
Hence, the correct answer is Option c.
