

It is usually easy to find the mass and volume of different solids and liquids. To find the mass of a solid, just place it on the scale. Finding the mass of a liquid is a little trickier. First find the mass of an empty container that will hold the liquid. Then fill the container with the designated amount of liquid and weigh it on the scale. The last step is to subtract the mass of the empty container from the mass of the container with the liquid. The difference is the mass of the liquid! Finding volume requires a different set of techniques. Pour the volume you want to find into a graduated cylinder or a beaker and read the volume in milliliters (ml). Measuring the volume of solids is a different process. If the solid in question is a regular square/rectangular shape, then you can find the volume by measuring it's length, width, and height. Multiply those three measurements, and you have found the volume. Make sure that your measurements are in centimeters (cm). This way your volume measurements are AUTOMATICALLY in volume units. In other words, one cubic centimeter (cm3) is the SAME as one milliliter (mL), which is the unit of measure displayed on graduated cylinders and beakers. If the solid is an irregular shape, the volume displacement method needs to be used. Use a beaker or graduated cylinder that can hold the solid. Put a specific amount of water into the container and record this volume. Next place the solid to be measured into the container and measure and record the volume of the water/solid combination. Subtract the original volume from the combined volume and the difference is the volume of the solid. But how do you measure the volume of a gas? How do you measure the mass of a gas? Does a gas like air have enough mass to measure in the lab? Does air weigh anything? It must weigh something, since it IS matter, and matter has both volume AND mass. This activity will give you a way to estimate the mass and volume of a gas like air. What kind of container can we use to hold the air? A beaker? A graduated cylinder? It would just leak out, and they are probably already filled with air, so these containers wouldn't work too well. We will use a balloon, since it is made just for this purpose! 

Problems: How can you estimate the mass of air? How can you estimate the density of a quantity of air? Will the density measurements change as the amount of air in the balloon increases? Hypothesis:


Materials (per group):


Safety concerns: Be sure to keep all chemical, heat, and glassware safety rules. Remember not to put a stopper into any flask unless given direct instruction by your teacher.  
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