The International System of Units (SI) is related to the metric system and is based on seven base units.
SI Base Units
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SI Units Concept 1
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When it comes to many of the calculations you're going to see in chemistry, science related courses, and math courses, you're gonna see that the metric system is oftentimes used. Now, the International System of Units, SI, is related to the metric system and is based on 7 base units. So here we have our 7 images, connected to them are their physical quantities, names, and symbols. For the first one, we have an anvil, and its physical quantity is discussing mass. For mass, the name of our SI unit is kilograms, and the symbol for kilograms is k g. Next, we have our ruler which represents length. The SI unit for length is meters, which is represented by m. For time, the name would be seconds. Seconds is illustrated by s. We have our thermometer, which deals with temperature. We know that there are 3 units for temperature, Kelvin, Celsius, and Fahrenheit, but it's Kelvin that represents our SI unit, and it's capital K. And then for remaining 3, we have the amount of a substance, which is the mole, We'll go into greater detail about the mole later on. Its symbol is just mol. Now you're gonna see sometimes when we're doing chemistry calculations, we might write out the entire word mole, or you might just use the symbol, interchanged with one another. Now next, we have electrical current, which is amperes, and that's just capital a. And then luminous intensity, the brightness of a light source, that's done by Candela, which is CD. So these represent our 7 SI units that you should commit to memory. And as we do different types of calculations, oftentimes we'll have to incorporate them within our calculations. Now that we've seen these examples, let's move on to our questions. We're gonna investigate more about the SI units.
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SI Units Concept 2
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Now that we've talked about SI units, we can apply them to other areas. For a classroom, for instance, we're gonna say here that we can take the SI units from up above and relate them to perimeter, area, and volume. 1st, let's take a look at perimeter. Perimeter can be thought of as this distance around an object. When it comes to a classroom lecture hall, all we have to do is add up all the sides of the object or figure, or in this case, the room to determine its perimeter. So if we take a look here, our typical classroom is 15 meters by 10 meters. To find the perimeter we just add up all the sides. So that'd be 15 meters, plus 10 meters, plus 15 meters, plus 10 meters. When we add them all up together, the perimeter of the classroom is 50 meters. Next, we can look at the area of the classroom. Area can be thought of as measured surface of an object as length squared. Now it's not actually just length squared, The formal, formula for area is area equals length times width. So that same classroom now, if we look at it in terms of feet, we could say here let's say that we reexamined it in terms of feet and we found these new measurements. And let's say that the lengths were 48 feet and the widths were 32 feet. So we would take 48 feet times the 32 feet, and that will give us our area. When we multiply those 2 together that'll give me 1536, and we're gonna say here that if we're multiplying feet times feet that would come out to be feet squared. Here we're not worrying too much about any greater detail. Our area here for the classroom would be 15 36 feet. Finally, we could talk about the volume of an object. If we're looking at volume, volume can be thought of as the space occupied by a 3 d object as length cubed. Now in actuality, the real formula is volume, which is v equals length times width times the height of the object. So here we have an example of a cube. We'd say here that its length is these 15 meters, its width is 10 meters, and its height is also 10 meters. So multiplying these together, 15 meters times 10 meters, times another 10 meters. So we multiply that all together that's going to give me 1500, and since it's meters times meters times meters that becomes meters cubed. Now notice for our area and our volume, we talked about length squared and here we have feet squared. And here we talked about length cubed, and here we got meters cubed. Taking the SI units that we examined up above, again, can be used in a lot of different ways. Here, we're using it to determine the perimeter area and volume of different objects. Now that we've looked at this example, move on to the practice question on the bottom of the page.
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Problem
Problem
Based on your knowledge of the SI base units, determine the units for the area of a typical chemistry laboratory.