There is a 2:1 ratio between H2 and O2. so for every mol of O2 used there would be 2 mol needed, so if we use 4 mol of O2 we multiply 4 by 2 to get 8 mol of H2 used in this reaction
Answer:
Explanation:
A physical change is one where only physical, not chemical, properties change. Let's analyze each answer choice.
A. Change in odor
- A change in order is one of the signs of a chemical change.
B. Chopping
- Chopping is a physical change, because no new substances are produced. However, it's not reversible. It's impossible to put something chopped back together again permanently.
C. Phase change
- A phase change is another physical change, plus it is reversible. For example, you can freeze water into ice and melt it back to water.
D. Rusting
- Rusting is a chemical change, because new substances are created.
So, the best answer choice for a reversible physical change is <u>C. phase change</u>.
<span> Advantages
- large resource of potential oil
- biggest resource is in Canada, whereas the largest reserves of crude oil are in Saudi Arabia and Venezuela
</span><span><span>- It requires less processing than oil shale and presents fewer problems than oil shale
- Processing is mainly by hot water.</span>- Exploitation has only started recently so low cost reserves are still available.
Disadvantages
- Most of the resource is uneconomic at present oil prices - so exploitable reserves are less than for crude oil
- Oil sands require mining, which is more complex and costly than drilling and pumping crude oil.
- Processing requires more energy than for crude oil.
- Resources are less than for oil shale - which is available in very large reserves in the US and Australia.</span>
<span>- Refining is more difficult because the product is in the form of bitumen - requiring cracking to produce a saleable product.
- because of the increased processing and refining, more carbon is released per unit of useable energy than for crude oil</span>
Technically speaking absolutely nothing but from a religious standpoint God did