Boiling point ..................................................
No. When water first begins to cool down, it contracts. However, as it gets colder and eventually freezes, it begins to expand.
You can test this by freezing water in a water bottle: when you take it out of the freezer, the cap might have popped off or cracks may have formed in the sides of the bottle.
Answer: Water expands when frozen, not contracts.
Answer:
H- hydrogen
Explanation: Hydrogen is in the first group meaning that it only has 1 valence electron and 1 energy level
Answer:
sp²
Explanation:
You need to look at how many electron orbitals around the atom. Looking at the structure below, you can see that there are three electron orbitals. This gives you an sp² hybridization.
Answer:
Option 3. The catalyst does not affect the enthalpy change (
) of a reaction.
Explanation:
As its name suggests, the enthalpy change of a reaction (
) is the difference between the enthalpy of the products and the reactants.
On the other hand, a catalyst speeds up a reaction because it provides an alternative reaction pathway from the reactants to the products.
In effect, a catalyst reduces the activation energy of the reaction in both directions. The reactants and products of the reaction won't change. As a result, the difference in their enthalpies won't change, either. That's the same as saying that the enthalpy change
of the reaction would stay the same.
Refer to an energy profile diagram. Enthalpy change of the reaction
measures the difference between the two horizontal sections. Indeed, the catalyst lowered the height of the peak. However, that did not change the height of each horizontal section or the difference between them. Hence, the enthalpy change of the reaction stayed the same.