Rubber.
Iron, copper, and graphite are minerals. Rubber is not a mineral.
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Answer:
d. Sum of product enthalpies minus the sum of reactant enthalpies
Explanation:
The standard enthalpy change of a reaction (ΔH°rxn) can be calculated using the following expression:
ΔH°rxn = ∑n(products) × ΔH°f(products) - ∑n(reactants) × ΔH°f(reactants)
where,
ni are the moles of products and reactants
ΔH°f(i) are the standard enthalpies of formation of products and reactants
Answer:
Explanation:
Step 1. Identify the Group that contains X
We look at the consecutive ionization energies and hunt for a big jump between them
We see a big jump between n = 2 and n = 3. This indicates that X has two valence electrons.
We can easily remove two electrons, but the third electron requires much more energy. That electron must be in the stable, filled, inner core.
So, X is in Group 2 and P is in Group 15.
Step 2. Identify the Compound
X can lose two valence electrons to reach a stable octet, and P can do the same by gaining three electrons.
We must have 3 X atoms for every 2 P atoms.
The formula of the compound is 
.
Answer:
Difference of the enthalpy (of a system) minus the product of the entropy and absolute temperature
Explanation:
The basis of spontaneity in a chemical reaction is that ∆G must be negative. ¡∆G is known as the change in free energy of a system. If ∆G is negative, then the reaction will occur without any external help (the reaction is spontaneous at room temperature).
∆G is given by;
∆G= ∆H -T∆S
Where;
∆H= change in enthalpy of the system
T= absolute temperature of the system
∆S= change in entropy
Hence; when ∆H -T∆S gives a negative result, the reaction proceeds without any external help.
