美国高考SATII化学专题解析The Ideal Gas Law
我们继续来看美国高考SATII化学专题解析The Ideal Gas Law，关于SATII化学，如果是为了800分满分做准备，同时各位同学也的确很愿意花时间，当然有老师指导的更好了，建议选择巴郎SAT化学；如果目标不是定的很高，同时时间也不是很充裕，我建议使用普林斯顿SAT化学。
The ideal gas law is the most important gas law for you to know: it combines all of the laws you learned about in this chapter thus far, under a set of standard conditions. The four conditions used to describe a gas—pressure, volume, temperature, and number of moles (quantity)—are all related, along with R, the universal gas law constant, in the following formula:
PV = nRT
where P = pressure (atm), V = volume (L), n = number of moles (mol), R = 0.08206 L · atm/mol · K, and T = temperature (K).
Now try an example using the ideal gas law equation.
Example
A 16.0 g sample of methane gas, CH4, the gas used in chemistry lab, has a volume of 5.0 L at 27ºC. Calculate the pressure.
Explanation
Looking at all the information given, you have a mass, a volume, and a temperature, and you need to find the pressure of the system. As always, start by checking your units. You must first convert 16.0 g of CH4 into moles: 16.0 g CH4
1 mol CH4/16.0 g CH4 = 1 mol of methane. The volume is in the correct units, but you must convert the temperature into Kelvins: 27 + 273 = 300K. Now you’re ready to plug these numbers into the ideal gas law equation:
PV = nRT
(P) (5.0 L) = (1.0 mol) (0.0821 L
atm/mol
K) (300K), so P = 4.9 atm
Don't let the math scare you. Remember that your test will be all multiple choice. You may be asked for proper setup, or at least you will have answers to choose from, and you won't have to do these lengthy calculations without a calculator. These examples are only meant to give you practice using the gas law equations.
SATII化学里面有很多东西都和原子结构什么的有很大关系，这部分知识要好好看。会考到一些实验题，个人认为考化学仪器什么的是很恶心的一部分，所以这种题就跳了。考试的时候发现有不少配平方程式的题，对中国学生是好事情。