High School Chemistry : Identifying Unknown Volume

In Chemistry, volume is often used in context with concentration or pressure. If looking for the volume of a solvent (given the moles, or weight of of solute, and the concentration) use V = n C If looking for the volume of a gas (given the pressure, moles, and temperature) use V = n R T P where R is the ideal gas constant and T is in Kelvin. The standard SI unit of volume is defined by the base unit of length (Figure 3). The standard volume is a cubic meter (m3), a cube with an edge length of exactly one meter. To dispense a cubic meter of water, we could build a cubic box with edge lengths of exactly one meter. This box would hold a cubic meter of water or any other substance.

The amount in moles of a solute in a given volume of solution can be calculated if the concentration of the solution is known. The mass of solute can then be calculated. Rearranging the equation for concentration below:. Calculate the amount of sodium hydroxide, NaOH, in Converting the volume from cm 3 to dm 3 If the amount in mol of a solute in a given volume of solution is known, its mass can also be calculated. For the example above, calculate the mass of NaOH in If the volumes of two solutions that react completely are known, and the concentration of one of the solutions is known, then the concentration of the other solution can be calculated.

Calculate the concentration of the NaOH solution. Converting volumes from cm 3 to dm 3 :. Substituting into the equation to find the amount of HCl in the given volume:.

So the amount of NaOH in Substituting into the equation to find the concentration of NaOH:. Volumes of solutions in reactions Calculating amounts from concentration and volume The amount in moles how many seasons of glee are there going to be a solute in a given volume of solution can be calculated if the concentration of the solution is known.

Question For the example above, calculate the mass of NaOH in

Example Questions

Feb 17, · Find: P 2 =? torr. List other known quantities. 1 L = mL to have the same units for volume. Plan the problem. 1. Perform the conversion of the second volume unit from L to mL. 2. Rearrange the equation algebraically to solve for \(P_2\). \[P_2 = \frac{P_1 \times V_1}{V_2}\] Cancel units and calculate. We can find the volume of concentrated acid necessary by setting the final volume and concentration equal to the initial concentration and unknown volume. The initial concentration is 2M, the final concentration is M, and the final volume is 50mL This means that mL of concentrated acid needs to be diluted to 50mL of solution. The formula used by this calculator to determine volume from mass and density is: V = m / ?. Symbols. V = Volume; m= Mass; ? = Density; Mass Measured. Enter the measured mass of the object and select the appropriate mass measuring units. Density of Substance. Enter the known density of the material being measured. Volume Calculation.

Last Updated: December 10, References. This article was co-authored by Grace Imson, MA. Grace Imson is a math teacher with over 40 years of teaching experience. She has taught math at the elementary, middle, high school, and college levels. There are 18 references cited in this article, which can be found at the bottom of the page. This article has been viewed 1,, times. The volume of a shape is the measure of how much three-dimensional space that shape takes up.

Common units of volume include cubic centimeters cm 3 , cubic meters m 3 , cubic inches in 3 , and cubic feet ft 3. You might notice that a lot of the volume formulas share similarities that can make them easier to remember. See if you can spot them along the way! If you need to learn how to calculate the volume of a sphere or pyramid, keep reading the article!

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Cookie Settings. Learn why people trust wikiHow. Download Article Explore this Article methods. Related Articles. Article Summary. Method 1 of Recognize a cube. A cube is a three-dimensional shape that has six identical square faces. A 6-sided die is a good example of a cube you might find in your house. Sugar cubes, and children's letter blocks are also usually cubes. Learn the formula for the volume of a cube.

Since all of the side lengths of a cube are the same, the formula for the volume of a cube is really easy. Find the length of one side of the cube. Depending on your assignment, the cube will either be labeled with this information, or you may have to measure the side length with a ruler.

Remember that since it is a cube, all of the side lengths should be equal so it doesn't matter which one you measure. If they are not, you will need to use the method below for Calculating the Volume of a Rectangular Solid. Make sure all of the lengths are in the same unit before multiplying them. Be sure to state your answer in cubic units. In the above example, the side length of our cube was measured in inches, so the volume was given in cubic inches. Method 2 of Recognize a rectangular solid.

A rectangular solid, also known as a rectangular prism, is a three-dimensional shape with six sides that are all rectangles. A cube is really just a special rectangular solid in which the sides of all of the rectangles are equal. Learn the formula for calculating the volume of a rectangular solid. Find the length of the rectangular solid.

The length is the longest side of the rectangular solid that is parallel to the ground or surface it is resting on. The length may be given in a diagram, or you may need to measure it with a ruler or tape measure. Don't worry too much about which side is the length, which is the width, etc. As long as you end up with three different measurements, the math will come out the same regardless of how your arrange the terms. Find the width of the rectangular solid. The width of the rectangular solid is the measurement of the shorter side of the solid, parallel to the ground or surface the shape is resting on.

Again, look for a label on the diagram indicating the width, or measure your shape with a ruler or tape measure. If you are measuring the rectangular solid with a ruler or tape measure, remember to take and record all measurements in the same units. Don't measure one side in inches another in centimeters; all measurements must use the same unit!

Find the height of the rectangular solid. This height is the distance from the ground or surface the rectangular solid is resting on to the top of the rectangular solid. Locate the information in your diagram, or measure the height using a ruler or tape measure. Plug the dimensions of the rectangular solid into the volume formula and calculate. Be sure to express your answer in cubic units. Since our example rectangle was measured in inches, the volume should be written as 72 cubic inches, or 72 in 3.

Method 3 of Learn to identify a cylinder. A cylinder is a three-dimensional shape that has two identical flat ends that are circular in shape, and a single curved side that connects them. Memorize the formula for the volume of a cylinder.

To calculate the volume of a cylinder, you must know its height and the radius of the circular base the distance from the center of the circle to its edge at the top and bottom. In some geometry problems the answer will be given in terms of pi, but in most cases it is sufficient to round pi to 3. Check with your instructor to find out what she would prefer. The formula for finding the volume of a cylinder is actually very similar to that for a rectangular solid: you are simply multiplying the height of the shape by the surface area of its base.

Find the radius of the base. If it is given in the diagram, simply use that number. Measure the object if the radius is not given. Be aware that getting precise measurement of a circular solid can be a bit tricky. One option is to measure the base of the cylinder across the top with a ruler or tape measure. Do your best to measure the width of the cylinder at its widest part, and divide that measurement by 2 to find the radius.

Another option is to measure the circumference of the cylinder the distance around it using a tape measure or a length of string that you can mark and then measure with a ruler.

For example, if the circumference you measured was 8 inches, the radius would be 1. If you need a really precise measurement, you might use both methods to make sure that your measurements are similar. If they are not, double check them.

The circumference method will usually yield more accurate results. Calculate the area of the circular base. You simply need to divide the diameter in half to find the radius. Find the height of the cylinder. This is simply the distance between the two circular bases, or the distance from the surface the cylinder is resting on to its top.

Find the label in your diagram that indicates the height of the cylinder, or measure the height with a ruler or tape measure. Multiply the area of the base times the height of the cylinder to find the volume. Remember to state your answer in cubic units. If our cylinder had been measured in centimeters, the volume would be expressed in cubic centimeters cm 3. Method 4 of Understand what a regular pyramid is. A pyramid is a three-dimensional shape with a polygon for a base, and lateral faces that taper at an apex the point of the pyramid.

A pyramid with a circular base is called a cone, which will be discussed in the next method. Learn the formula for the volume of a regular pyramid. The volume formula is the same for right pyramids, in which the apex is directly above the center of the base, and for oblique pyramids, in which the apex is not centered. Calculate the area of the base. The formula for this will depend on the number of sides the base of the pyramid has.

In the pyramid in our diagram, the base is a square with sides that are 6 inches in length. So for this pyramid, the area of the base is 6 in 2 , or 36in 2. This is a pretty involved calculation that goes beyond the scope of this article, but check out Calculate the Area of a Polygon for some great instructions on how to use it. Or you can make your life easy and search for a Regular Polygon Calculator online.

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