***SAFETY PROCEDURE*** WEAR YOUR SAFETY GOGGLES AND APRON.
PHYSICAL AND CHEMICAL CHANGES
Purpose: In this experiment you will observe some physical and some chemical changes. You will observe that energy must be used to start some chemical reactions, and that it is produced in others.
Apparatus: Forceps Bunsen burner Funnel Wire gauze Crucible tongs Filter paper Test tubes, large and small Universal clamp Test tube rack Stirring rod Ring stand and ring Materials: Nichrome metal Magnesium metal Wooden splints Sodium chloride solution, NaCl, 0.1 M Hydrochloric acid, HCl, 3M Silver nitrate solution, AgNO3, 0.1M Steel wool Sodium hydrogen carbonate, NaHCO3, solid Zinc metal, Zn
Theory: Matter
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Procedure:
For each step record observations and conclusions in your data table.
l. NICHROME - APPEARANCE AND REACTION TO HEAT Examine a piece of nichrome wire. On the data sheet, record the color and the luster of the metal. Use a forceps to hold the wire in the flame of your burner for about two minutes (recall where the hottest part of the flame is located). Describe the appearance of the wire while held in the hottest part of the flame. Allow the wire to cool and reexamine it. From your observations, determine if there was a physical or a chemical change. Give specific reasons for your conclusions. Save the nichrome wire for step #2.
2. NICHROME - REACTION WITH ACID
***SAFETY PROCEDURE*** HYDROCHLORIC ACID IS A CORROSIVE SUBSTANCE WHICH CAN CAUSE DAMAGE TO SKIN AND OTHER SUBSTANCES. IT HAS STRONG VAPORS. WEAR GOGGLES AND AN APRON. YOUR TEACHER WILL SHOW YOU HOW TO POUR THE ACID SAFELY. IF YOU SPILL ACID ON YOURSELF, WASH IT OFF WITH LOTS OF RUNNING WATER. A FEW DROPS SPILLED ON THE LAB BENCH CAN BE CLEANED UP WITH A PAPER TOWEL. A LARGE SPILL SHOULD BE NEUTRALIZED WITH BAKING SODA, AND THE RESULTING NEUTRAL SUBSTANCE CAN THEN BE WASHED INTO THE SINK WITH A
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Give specific evidence for your conclusions.
1. Nichrome and heat The nichrome wire is silver with a sort of rusty brown color on portions of it and is not slightly shiny. When the nichrome wire was put into the heat (bunsen burner), the flame turned from blue to orange, and the wire began glowing orange in the part touching the flame. This was a physical change because the only thing that changed was the color was changed but went back to normal, thus indicating that the composition has not changed.
2. Nichrome and hydrochloric acid The nichrome wire exposed to the acid there was nothing that occurred. Therefore, it was neither a chemical nor physical change.
3. Zinc and hydrochloric acid When the zinc was dropped in the hydrochloric acid, the substance began bubbling vigorously, forming a precipitate. Eventually, the zinc dissolved completely. After the lit wooden splint broke the surface of the test tube, there was a loud popping noise. The gas that was released was hydrogen from the acid and the popping noise was a result of the Hydrogen being burned up by the fire creating a small explosion. Two chemical changes occurred in this test: one with the formation of a precipitate (a textbook sign of a chemical change), and the other when the explosion
One of the signs of a chemical change is that sound is produced. The oxygen, fire and hydrogen react together, creating a popping noise (this is the hydrogen combusting).
3. Carefully felt the sides of the test tube and observed the resulted chemical reaction for about 30 seconds.
Procedure: In this experiment, various chemicals were mixed together, to determine a reaction. Using two drops from chemical 1 and two drops of chemical two, unless otherwise stated, then recording the type of physical reaction or color changes that occurred.
The main objective of this experiment is to differentiate between a physical change and a chemical change.
These reactions can be seen from just a little bit of reaction all the way up to a complete change of the entire sample tested. Some samples of those tested in this experiment which showed the chemical reaction were the baking soda/ammonia mixture, the Epson salt and baking soda mixture as well as the food coloring mixed with the baking soda and bleach. 2. Which reactions, if any, do you believe showed no evidence of chemical change? Justify your reasoning.
A chemical reaction is when substances (reactants) change into other substances (products). The five general types of chemical reactions are synthesis (also known as direct combination), decomposition, single replacement (also known as single displacement), double replacement (also known as double displacement), and combustion. In this lab, the five general types of chemical reactions were conducted and observations were taken before, during, and after the reaction. Then the reactants and observations were used to determine the products to form a balanced chemical equation. The purpose of this lab was to learn and answer the question: How can observations be used to determine the identity of substances produced in a chemical reaction?
Product bubbled upon addition to the hydrochloric acid; liquid turned cloudy ¡V precipitate was present; zinc sample disintegrated slowly and turned black in color.
| NaHCO₃ reacts with the hydrochloric acid by heating up violently, bubbling, dissolves, and new gas formation
Eleven mystery test tubes labeled from K-1 to K-11 contained: 6M H2SO4, 6M NH3, 6M HCl, 6M NaOH, 1M NaCl, 1M Fe(NO3)3, 1M NiSO4, 1M AgNO3, 1M KSCN, 1M Ba(NO3)2, 1M Cu(NO3)2 respectively. The contents of the test tubes were determined by chemical experiments. Solution K-1 contained NiSO4 because when solution K-9, ammonia which was identified by its pungent odor, was added, an inky dark blue color was made. Iron (Fe (NO3)3) was determined to be in test tube K-2. KSCN was found in test tube K-11 since Fe (NO3)3 and KSCN makes a bloody color when mixed together. Flame tests were conducted in which K-8
In this lab we will be heating up substances and use them to galvanize pennies. When you heat up the zinc, and then coat the penny in it, it then galvanizes the penny. Meaning, it helps protect the penny from oxygen and water. Afterwards, you will need to record data such as the mass of the penny. This helps keep track of what physical traits are being changed during this experiment. On part B of this experiment, you will be heating up the now galvanized pennies in order to see what reaction you get. The reaction you should receive from heating up the now zinc-covered pennies is that the pennies will change color.
Working in the hood or a designated work area, add about 1 mL of ethyl alcohol to a clean evaporating dish. Place the evaporating dish on a heat- resistant pad.
Hypothesis: Reaction 3 will create the highest exothermic reaction in the test tube this is because the chemicals are highly flammable the means they are high in exothermic relations. If we use 4 grams of zinc powder the chemical retain with the copper sulphate solution will create the highest temperature We changed the
12) Find and extract the remaining copper wire out of the mixture using forceps and rinse the copper wire with distilled water so that the water goes into the plastic container.
Safety glasses: Wear safety glasses to protect eyes from substances, acids and flames that can irritate or damage the eyes.
Part A.1. Sodium metal is also readily oxidized by oxygen. If the product of the reaction were dissolved in water, what would be the color of the litmus for a litmus test? Explain. What is the product?