Chemistry—Semester B

A record of what happens when we bring chemicals together and apply heat.

  • Credit Recovery Enabled
  • Course Length: 18 weeks
  • Course Type: Basic
  • Category:
    • Science
    • High School

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Shmoop's Chemistry course has been granted a-g certification, which means it has met the rigorous iNACOL Standards for Quality Online Courses and will now be honored as part of the requirements for admission into the University of California system.

This course has also been certified by Quality Matters, a trusted quality assurance organization that provides course review services to certify the quality of online and blended courses.


All right, so we know the basics about chemistry: what atoms are made of, what they look like (if we had super-powered zoom vision), and how they stick together to make the molecules we know and love (we're looking at you, sugar and caffeine). Now it's time to dive into what chemistry is really all about—and no, we're not talking about controlled laboratory explosions, although that's part of it.

At the heart of this course are chemical reactions. How exactly do all those persnickety elements manage to bond together and make compounds? How come sometimes those reactions give off enough heat to burst into flames, and other times suck in enough heat from their surroundings to form ice? And most importantly, what happens if we fiddle with subatomic particles themselves? Can we make a fission-powered snow cone machine, or maybe a fusion-powered oven that will bake cupcakes faster?

In this course, we'll talk about:

  • chemical reactions, including synthesis, decomposition, displacement, and yeah, combustion reactions.
  • stoichiometry, which will help us understand ratios, yields, and limiting reagents.
  • everything we ever wanted to know about solutions, and probably a couple of things we didn't want to know about solutions.
  • thermodynamics, which is the study of how heat, energy, and disorder play into chemical reactions.
  • organic chemistry, a.k.a. the chemistry of stuff that makes life possible.
  • and a healthy dose of nuclear chemistry and environmental chemistry, not that those two things go hand-in-hand.

Sounds like a lot, but not to worry. Each lesson is highly (re)active, and includes glossaries, readings, and activities that are tagged with the Next Generation Standards (NGSS), so we have all the bases covered.

P.S. This is Semester B of a two-semester course. You can check out Semester A here.

Required Skills

  • Knowledge of Algebra concepts. 
  • Chemistry—Semester A


Unit Breakdown

10 Chemistry—Semester B - Chemical Reactions

Chemistry wouldn't be so useful and fun if we couldn't make stuff with it. That's what this unit is all about—the reactions that let us go from the boring, everyday chemicals we have on hand to a new, exciting set of products. Who knows what we'll get? Soon, you will.

11 Chemistry—Semester B - Stoichiometry

Put away your crystal ball and cancel your subscription to Psychics Monthly—this unit has the real deal when it comes to predicting the future. Using stoichiometry, we'll be able to predict who, what, and how much of any chemical reaction. They aren't winning Lotto numbers, but you'll still be able to impress with your powers of prognostication.

12 Chemistry—Semester B - Gas Laws

Do you get gas? If so, you might want to to take an antacid (and open a window in the meantime). If not, you'll want to take this unit, which is all about the laws that govern gases' behavior. How do the pressure, temperature, and volume of a gas all relate to each other? We'll clear the air and give you all the details.

13 Chemistry—Semester B - Solutions

When you think of a chemist, you probably picture somebody in a lab coat and goggles, swishing chemicals around in beakers. Well, chances are good that the stuff in those beakers are suspended in a solution, so this unit is key to fulfilling all of your wildest chemist- and/or chemistry-related fantasies.

14 Chemistry—Semester B - Thermodynamics and Kinetics

Is it getting hot in here, or is it just this unit? Wait, it's definitely this unit, because it's all about thermodynamics: the movement of heat. Knowing about this stuff is good for more than deciding when to turn on the thermostat—it also lets us predict which reactions will happen without even saying "hello," and which ones need a bit of a kick start to get going.

15 Chemistry—Semester B - Equilibrium

The last couple units are pretty math-intensive, so this one will help you find your equilibrium. And chemical equilibriums as well. See, chemical reactions are technically two-way streets, and finding the reaction's equilibrium constant will let us figure out the flow of traffic. They're not as convenient as signs on the side of the road, but a lot easier to read when we're working at the atomic level.

16 Chemistry—Semester B - Acids and Bases

Is it getting acidic and basic in here, or is it just...wait, we did this joke already. Anyway, acids and bases have all kinds of special rules for their reactions. They're swapping around protons like they're at a swap meet. In this unit, we'll identify, classify, and analyze all kinds of acids and bases.

17 Chemistry—Semester B - Organic Chemistry Basics

Not all that glitters is gold, and not all that's organic is good eating, either. That's because calling something "organic" isn't just about all the farm-fresh goodies at the local farmer's market; gasoline is an organic molecule, too, and you don't see us filling up our tea cups at the pump. In this unit, we'll go over what it means for a chemical to be organic, along with some of the chemical oddities that make organic compounds so important to life as we know it.

18 Chemistry—Semester B - Nuclear Chemistry

We'll be learning about nuclear power in this unit. Calm down and cancel your Amazon order for a hazmat suit—it's not going to be that bad. We'll cover exactly what nuclear radiation is (as opposed to what Marvel tells you it is) and how to calculate how much nuclear material has decayed as time passes. Then we'll talk a bit about the pros and cons of nuclear energy, and even about our good buddy, the Sun. If nuclear power was so dangerous, would they really be able to keep Raisin Bran cereal on the shelves?

19 Chemistry—Semester B - Environmental Chemistry

We're going to wind down at the end of this course with some chemistry of the environmental kind. We'll apply what we've learned to explore humanity's impact on the environment, as seen through the lens of chemical reactions. And a thick layer of smog. We're kind of ending on a downer here. Whoops.


Recommended prerequisites:

  • Algebra I—Semester A
  • Algebra I—Semester B
  • Chemistry—Semester A

  • Sample Lesson - Introduction

    Lesson 14.04: Latent Heat and Phase Changes

    Have you ever had one of those lazy summer days? A day with nothing better to do than just sit around, contemplating how much heat you'd need to add to the ice in your lemonade to make it melt completely?

    We have, and let us just say that those are some of the best days ever. Here's why:

    • We are sitting
    • We have a glass of lemonade
    • We're working our chemistry mojo


    Kid Selling Lemonade at a Lemonade Stand
    Lemonade: good for drinking and thinking.

    (Source)

    Too bad you have to actually sell lemonade to make money. If we got paid for just thinking about it, we'd be rich.

    In this lesson, we're going to revisit phase changes and discuss what's happening in terms of thermal energy transfer. We'll level up our phase change vocabulary with terms like "latent heat," "heat of vaporization," and "heat of fusion." 

    Sound impressive? Yeah, it's gonna be. Get ready to enjoy a full cranium workout, all without leaving the comfort of your computer chair.


    Sample Lesson - Reading

    Reading 14.14.04: Fun with Phase Changes

    So far in this unit, we've learned how heat energy can be transferred in the form of work or…well, heat. There is also a third way that energy can be transferred in chemical systems, and that's through phase changes. It's been a little while since we talked about phase changes, so if you need a refresher on the terminology, feel free to re-read this learning guide.

    Once you're back up to speed, here are the key concepts we need to understand when it comes to heat and phase changes:

    • As a substance changes from solid → liquid → gas, the heat in the system increases (+ΔH).
    • As a substance changes from gas → liquid → solid, the heat in the system decreases (-ΔH).
    • During the transition from one phase to another, the heat energy is held constant. So for example, boiling water stays at 100° in liquid form, no matter how hot we blast our Bunsen burner. The water can only go above 100° once it's transitioned into its gas state.
    • Latent heat is the amount of heat energy needed to melt or boil a substance.
    • Different substances have specific latent heats for melting and boiling.
    • The specific latent heat for boiling is also known as the heat of vaporizationHvap) and is measured in J/kg or J/g.
    • The specific latent heat for melting is also known as the heat of fusionHfus) and is measured in J/kg or J/g.

    The latent heat of fusion and vaporization for different elements and compounds are figured out by experiments. Chemist do love their lab experiments. When it comes to calculating problems dealing with specific latent heats for boiling, you'll be provided those values. They'll probably come in a table like this.

    When it comes to doing energy calculations for phase changes, we have a formula, of course. To get all the deets on what that formula is and how it works, head to this Shmoop learning guide and scroll down to read the section called “Phase Changes.”

    Basically, the latent heat formula is the same as the specific heat formula. The only differences are that we use our latent heat value (L) instead of the specific heat valued (c); and also, the temperature doesn’t change during a phase change, so we have no ΔT in the formula.

    Doing the calculations is pretty easy. We just find our L value on a chart, and then plug it in along with our substance’s mass to figure out the energy needed to make our phase change happen.

    So for example, we could calculate how much energy is needed to melt 0.40 kg of ice by simply finding the latent heat of fusion on our table above. 334 kJ/kg. From there, we just plug our numbers into the formula.

    Q = mL

    Q = (0.40)(334) = 134 kJ

    We can also utilize the heating curve of a substance to determine the amount of energy needed during each phase change.

    We love images to help us process what we're learning. Here are two that we like to keep in our back pocket:


    The basics of a heating curve


    The basics of a cooling curve

    As we can see on the two graphs, our phase changes happen in those spots where the heating curve is flat. To figure out the latent heat for any phase change, we just need to look at our heat value on the x-axis. Specifically, we want to subtract the initial heat from the final heat during the phase change, or in other words, QfinalQinitial = Qtotal.

    Again, to be double clear, we’re talking about the final and initial heat values during the flat spot on our curve where the phase change is happening. Just make sure to pick the correct flat spot that corresponds with whichever phase change we’re interested in, and we're good to go.

    Not too shabby, right? Time to put it all together with our activity.


    Sample Lesson - Activity

    Activity 14.04a: Hyped for Heating Curves

    1. The heating curve below is for a pure unknown substance, which was heated by a constant source of heat that supplied 1600 Joules/minute.

      Identify the portion of the heating curve referred to in each of the following questions. For questions 1 – 5, use the labeled data points to name the appropriate section. (For example, the answer could be the point D or segment BC, etc.).

      1. Where is the substance being warmed as a solid?

      2. Where is the substance being warmed as a liquid?

      3. Where is the substance being warmed as a gas?

      4. Where is the substance changing from a solid to a liquid?

      5. Where is the substance changing from a liquid to a gas?

      6. What is its boiling temperature?

      7. What is its melting temperature?

    2. The following data show the amount of time needed to go through each phase of the substance.

      AB = 0.4 min, BC = 4.0 min, CD = 4.0 min, DE = 19.8 min, EF = 1.0 min

      1. How many joules were needed to change the liquid to a gas?

      2. If the sample weighs 10.0 g, what is its heat of vaporization in J/g?

      3. Where on the curve do the molecules have the highest kinetic energy?


    Sample Lesson - Activity

    1. Which of the following statements is false?

    2. What is another name for the specific latent heat of melting?

    3. Review this passage and answer the following questions:

      Use the following information to answer questions 3-5:

      You are given a sample of H2O with mass 25.0 grams at a temperature of -48.0 °C. You are also given this table of the specific heats of the phases of water.

    4. How many kilojoules of heat energy are necessary to heat the ice to 0.0 °C?

    5. How many kilojoules of heat energy are needed to change the temperature of the water from 0 °C to 100 °C?

    6. What can be said about the ΔH in questions 3 and 4?