How to Find the Volume in a Test Tube

How to Find the Volume in a Test Tube Finding the volume of a test tube or NMR tube is a common chemistry calculation, both in the lab for practical reasons and in the classroom to learn how to convert units and report significant figures. Here are three ways to find the volume. Calculate Density Using Volume of a Cylinder A typical test tube has a rounded bottom, but NMR tubes and certain other test tubes have a flat bottom, so the volume contained in them is a cylinder. You can get a reasonably accurate measure of volume by measuring the internal diameter of the tube and the height of the liquid. The best way to measure the diameter of a test tube is to measure the widest distance between the inside glass or plastic surfaces. If you measure all the way from edge to edge, youll include the test tube itself in your measurements, which isnt correct.Measure the volume of the sample from where it starts at the bottom of the tube to the base of the meniscus (for liquids) or the top layer of the sample. Dont measure the test tube from the bottom of the base to where it ends. Use the formula for the volume of a cylinder to perform the calculation: V Ï€r2h where V is volume, Ï€ is pi (about 3.14 or 3.14159), r is the radius of the cylinder and h is the height of the sample The diameter (which you measured) is twice the radius (or radius is one-half diameter), so the equation may be rewritten: V Ï€(1/2 d)2h where d is diameter Example Volume Calculation Lets say you measure an NMR tube and find the diameter to be 18.1 mm and height to be 3.24 cm. Calculate the volume. Report your answer to the nearest 0.1 ml. First, youll want to convert the units so theyre the same. Please use cm as your units, because a cubic centimeter is a milliliter! This will save you trouble when it comes time to report your volume. There are 10 mm in 1 cm, so to convert 18.1 mm into cm: diameter (18.1 mm) x (1 cm/10 mm) [note how the mm cancels out]diameter 1.81 cm Now, plug in the values into the volume equation: V Ï€(1/2 d)2hV (3.14)(1.81 cm/ 2)2(3.12 cm)V 8.024 cm3 [from the calculator] Because there is 1 ml in 1 cubic centimeter: V 8.024 ml But, this is unrealistic precision, given your measurements. If you report the value to the nearest 0.1 ml, the answer is: V 8.0 ml Find the Volume of a Test Tube Using Density If you know the composition of the contents of the test tube, you can look up its density to find the volume. Remember, density equal mass per unit volume. Get the mass of the empty test tube. Get the mass of the test tube plus the sample. The mass of the sample is: mass (mass of filled test tube) – (mass of empty test tube) Now, use the density of the sample to find its volume. Make sure the units of density are the same as those of the mass and volume you want to report. You may need to convert units. density (mass of sample) / (volume of sample) Rearranging the equation: Volume Density x Mass Expect error in this calculation from your mass measurements and from any difference between the reported density and the actual density. This usually happens if your sample isnt pure or the temperature is different from the one used for the density measurement. Finding the Volume of a Test Tube Using a Graduated Cylinder Notice a normal test tube has a rounded bottom. This means using the formula for the  volume of a cylinder will produce an error in your calculation. Also, its tricky trying to measure the internal diameter of the tube. The best way to find the volume of the test tube is to transfer the liquid to a clean graduated cylinder to take a reading. Note there will be some error in this measurement, too. A small volume of liquid may be left behind in the test tube during transfer to the graduated cylinder. Almost certainly, some of the sample will remain in the graduated cylinder when you transfer it back to the test tube. Take this into account. Combining Formulas to Get Volume Yet another method to get the volume of a rounded test tube is to combine the volume of a cylinder with half the volume of the sphere (the hemisphere that is the rounded bottom). Be aware that the thickness of the glass at the bottom of the tube may be different from that of the walls, so there is an inherent error in this calculation.

Memorial Day Quotes by Ronald Reagan

Memorial Day Quotes by Ronald Reagan Fortieth President of the United States, Ronald Reagan was a man of many colors. Starting his career as a radio broadcaster and then as an actor, Reagan moved on to serve the nation as a soldier. He finally jumped into the political arena to become one of the stalwarts of American politics. Although he started his political career quite late in life, it took him no time to reach the Holy Grail of US politics. Ronald Reagan won the elections and was appointed as the President of United States of America in 1980. Reagan Was a Good Communicator It is a well-known fact that Ronald Reagan was a good communicator. His speeches inspired millions all over the world. He had the knack of reaching every American soul with his stirring words. His critics dismissed his achievements, claiming that he smooth-talked his way into the White House. But he silenced his critics by serving two full terms as President. Reagan proved that he was not full of hot air; he was a President who meant business. Military Climate During Reagans Tenure When Reagan became ​president, he had inherited a disheartened military, which had gone through the ravages of the Vietnam War. But Reagan saw this as an opportunity for America to brace herself through the Cold War. In fact, Reagan was instrumental in bringing the Cold War to an end because of his suave diplomacy and calculated military strategies. It was the dawn of a new era in American politics. Reagan, along with his Russian compatriot Mikhail Gorbachev had accelerated the peace movement by ending the Cold War. Soviet Unions Love-Hate Relationship With Reagan Ronald Reagan hugely appreciated American values of freedom, liberty, and unity. He espoused these principles in his speeches. Reagan spoke about his vision of a vibrant America, calling it a shining city on a hill. He later clarified his metaphor by saying, In my mind, it was a tall proud city built on rocks stronger than oceans, wind-swept, God-blessed, and teeming with people of all kinds living in harmony and peace.Though Reagan was widely criticized for building up the arms race with the Soviet Union, many understood this as a necessary evil to mitigate the Cold War. Reagans gamble paid off when the Soviet Union, encouraged by Americas flexed muscles, chose to pull the nuclear arms race into reverse gear. Reagan expressed his revulsion for war by saying, It is not bombs and rockets but belief and resolve it is humility before God that is ultimately the source of Americas strength as a nation. Reagans Famous Words on Memorial Day On Memorial Day, Ronald Reagan addressed America with passionate words. His words touched a chord in every heart. Reagan spoke of patriotism, heroism, and freedom in moving words. His impassioned speeches reminded Americans that they had bought their freedom with the blood of the martyrs who died defending the nation. Reagan heaped praise on the families of martyrs and veterans. Read some Memorial Day quotes by Ronald Reagan below. If you share his enthusiasm and spirit, spread the message of peace on Memorial Day.   May 26, 1983:  I dont have to tell you how fragile this precious gift of freedom is. Every time we hear, watch or read the news, we are reminded that liberty is a rare commodity in this world.Arlington National Cemetery, May 31, 1982:  The United States and the freedom for which it stands, the freedom for which they died, must endure and prosper. Their lives remind us that freedom is not bought cheaply. It has a cost; it imposes a burden. And just as they whom we commemorate were willing to sacrifice, so too must we- in a less final, less heroic way be willing to give of ourselves.May 25, 1981:  Today, the United States stands as a beacon of liberty and democratic strength before the community of nations. We are resolved to stand firm against those who would destroy the freedoms we cherish. We are determined to achieve an enduring peace- a peace with liberty and with honor. This determination, this resolve, is the highest tribute we can pay to the many who have fallen in the s ervice of our Nation. Arlington National Cemetery, May 31, 1982Our goal is peace. We can gain that peace by strengthening our alliances, by speaking candidly about the dangers before us, by assuring potential adversaries of our seriousness, by actively pursuing every chance of honest and fruitful negotiation.May 26, 1983:  We owe this freedom of choice and action to those men and women in uniform who have served this nation and its interests in time of need. In particular, we are forever indebted to those who have given their lives that we might be free.Arlington National Cemetery, May 31, 1982:  I cant claim to know the words of all the national anthems in the world, but I dont know of any other that ends with a question and a challenge as ours does: Does that flag still wave oer the land of the free and the home of the brave? That is what we must all ask.October 27, 1964:  You and I have a rendezvous with destiny. We will preserve for our children this, the last best hope of man on earth, or we wi ll sentence them to take the first step into a thousand years of darkness. If we fail, at least let our children and our childrens children say of us we justified our brief moment here. We did all that could be done. Phoenix Chamber of Commerce, March 30, 1961:  Freedom is never more than one generation away from extinction. We did not pass it to our children in the bloodstream. It must be fought for, protected, and handed on for them to do the same, or one day we will spend our sunset years telling our children and our childrens children what it was once like in the United States where men were free.