# Question Video: Describing How a Balance Can Be Used to Measure the Mass of a Solid Chemistry

Put the following statements in the correct order to describe how a balance should be used to measure the mass of a solid. (a) Set the balance to zero. (b) Record the final mass of the sample. (c) Place the container onto the mass balance. (d) Weigh out the substance into the container.

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### Video Transcript

Put the following statements in the correct order to describe how a balance should be used to measure the mass of a solid. (a) Set the balance to zero. (b) Record the final mass of the sample. (c) Place the container onto the mass balance. (d) Weigh out the substance into the container.

A balance is an instrument used to measure mass. There are many types of electronic balances that we may encounter in the chemistry laboratory. The most commonly used electronic balance is accurate to two decimal places and is known as a two-figure balance or top loading balance. On top of the balance is a metal pan, where we place the objects we wish to mass. A digital display shows the mass to two decimal places. The zero or Tare button allows us to set the display to zero. The question asks us to put the following statements in the correct order to describe how a balance like this one should be used to measure the mass of a solid.

Let’s discuss how we would use this two-figure balance to measure the mass of a solid like copper sulfate. Firstly, we don’t want to place the chemicals directly on the metal pan, so we’ll need a container like a beaker or a disposable plastic weigh boat. If the only step we take is to place the weigh boat and copper sulfate directly on the balance, then the mass displayed is the mass of the copper sulfate and the weigh boat. But we just want the mass of copper sulfate, the solid. So we should start by placing an empty weigh boat on the balance. Then, we should press the zero or Tare button. This sets the balance to zero and effectively tells the balance to ignore the mass of the weigh boat.

Next, we should add our solid to the weigh boat. It’s best practice to remove the weigh boat from the balance before adding the solid. This is to prevent spilling material onto the balance pan and potentially damaging the mechanism inside. We’ll notice that when we remove the weigh boat from the balance, the balance will display a negative mass. The mass is negative because the balance will subtract this mass from the mass of whatever is placed on the pan. So if we now place the weigh boat and the copper sulfate on the balance, the balance will automatically subtract the mass of the weigh boat and display only the mass of the copper sulfate.

We can now record the final mass of the sample. We now know that the steps in order are (c) place the container onto the mass balance, (a) set the balance to zero, (d) weigh out the substance into the container, and (b) record the final mass of the sample. So the correct order of the statements to describe how a balance should be used to measure the mass of a solid is (c), (a), (d), (b).