1. Chemical Measurements

SI Units

TheÂ **International System of Units** (SI) is system of units of measurements based around the number 10.Â

SI Units

1

example

## SI Units vs. Derived Units

3m

Play a video:

Was this helpful?

in this video, we'll take a look at the S. I. Units as we explore calculations in analytical chemistry. It'll be important to commit to memory some of our S. I. Base units as well as R. S. I. Derived units. So if we take a look, it says that the international system of units provide nine units of measurement that are gonna be used when we're talking about S. I. Units. Now when it comes to the S. I. Base units, we're gonna have these nine physical quantities being discussed. Of these nine, I would say the first six are the most important. So if we take a look when it comes to mass, the symbol that we use or the units that we talk about, our kilograms for length, we're discussing meters time will be in seconds. Uh temperature will be in kelvin amounts of any substance. No matter what it is, we use one mole to talk about that amount. Um When it comes to electrical current or amps um we're discussing amperes, the symbol here would just be a, remember an ampere is just charge per time, which would be cool items per second. Um The final three, which deals with luminous intensity, plane angle as well as solid angle. Um There other S. I. Based units but they're less important in the first six. The other six will will discover in some way or another whether we're doing some type of stoking metric calculations or with electrical current. When we're talking about electoral chemistry. Now from these S. I. Based units, we have R. S. I. Derived units. Now here. when we're talking about frequency. Remember it's connected to the electromagnetic spectrum. And when we talk about the electromagnetic spectrum, we talk about frequency wavelength energy frequency uses hurts for its units. And here from the S. I. Based units, it's just seconds inverse or one over seconds. When we're talking about force, we're talking about Newton's here doesn't have any S. I. Derived units. It's S. I. Base units would be meters times kilograms over seconds squared pressure. We're used to seeing atmospheres being discussed. But really when it comes to R. S. I. Derived units, we're really talking about pascal's and here, remember there are R. S. I. Derived units which are the newtons which we talked about with force over meters squared. And then we have our S. I. Base units. When we're talking about energy work or quantity of heat involved, we're talking about jules. This is typically done when we're talking about chemical thermodynamics. If we're talking about entropy entropy gibbs, free energy. Or if we're talking about thermal chemistry when we're discussing heat power. When we talk about Electoral Chemistry, we'll talk about current, we'll talk about watts. We'll talk about things like that resistance. Electrical charge we discussed up above. Remember when we talked about and peers is being charged per time here. When we're talking about charge, the unit is the cool um potential is voltage these last for all deal with electro chemistry. They have some physics um involved with them. When we get to the electro chemistry chapter, we'll talk in greater detail about these last four in particular, but just remember we have our S. I. Base units and the S. I. Base units are connected to our S. I. Derived units as well. So keep in memory some of the most common ones that we will tend to see as we progress deeper and deeper into analytical chemistry.

The** International System of Units (SI)** provides 9 units of measurement as the foundation from which all other SI units can be derived.

**Derived Units** are generated through mathematical relationships between the **base units**. They represent a combination of the base quantities.