Which combinations of substances resulted in a chemical change

Type of paper: Report. Answer 1: The mixture of ammonium vanadate, ammonium hydroxide, and hydrochloric acid was yellowish and had less color in comparison with the control. As Manganese sulfate was mixed with ammonium hydroxide turned into orange, Though as it was mixed with hydrochloric acid its color did not changed and stayed clear. The control of iron nitrate was orange, but as it was mixed with ammonium hydroxide the color changed into red and after mixing with hydrochloric acid the color was yellow.

The control of cobalt nitrate was pink. When it was mixed with hydrochloric acid the color did not change but as it was mixed ammonium hydroxide, the color turned into purple. The control of copper nitrate was clear. It was mixed with hydrochloric acid the color did not change but as it was mixed ammonium hydroxide, the color turned into blue.

The control of zinc nitrate was also clear. It was mixed with hydrochloric acid the color did not change but as it was mixed ammonium hydroxide, the structure changed into a hard structure, like a crystal. For each metal that participated in a chemical change, write the type of metal it is, based on your examination of the periodic table.

Ammonium Vanadate seems to be a post transition metal. The other transition metals are: Iron nitrate, copper nitrate, cobalt nitrate, and zinc nitrate. Were there any metallic compounds that did not react with either the acid or the base? Write the type of metal, based on your examination of the periodic table. Among metallic compounds only potassium nitrate and calcium nitrate did not react. Question 4: Make a general statement about the reactivity of the metals in this experiment.

Answer 4: During this experiment all transition metals had a reaction as they were mixed with the other substance. However potassium nitrate which is an alkali metal and calcium nitrate which is an alkaline earth metal had no reaction at all.

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The melted ice cube may be refrozen, so melting is a reversible physical change. Physical changes that involve a change of state are all reversible. Other changes of state include vaporization liquid to gas , freezing liquid to solid , and condensation gas to liquid. Dissolving is also a reversible physical change. When salt is dissolved into water, the salt is said to have entered the aqueous state. The salt may be regained by boiling off the water, leaving the salt behind.

This means that one substance with a certain set of properties such as melting point, color, taste, etc is turned into a different substance with different properties.

Chemical changes are frequently harder to reverse than physical changes. One good example of a chemical change is burning a candle. The act of burning paper actually results in the formation of new chemicals carbon dioxide and water from the burning of the wax.

Another example of a chemical change is what occurs when natural gas is burned in your furnace. In this case, not only has the appearance changed, but the structure of the molecules has also changed.

The new substances do not have the same chemical properties as the original ones. Therefore, this is a chemical change. We can't actually see molecules breaking and forming bonds, although that's what defines chemical changes. We have to make other observations to indicate that a chemical change has happened. Some of the evidence for chemical change will involve the energy changes that occur in chemical changes, but some evidence involves the fact that new substances with different properties are formed in a chemical change.

Label each of the following changes as a physical or chemical change. Give evidence to support your answer. Homogeneous mixtures solutions can be separated into their component substances by physical processes that rely on differences in some physical property, such as differences in their boiling points. Two of these separation methods are distillation and crystallization. Distillation makes use of differences in volatility, a measure of how easily a substance is converted to a gas at a given temperature.

A simple distillation apparatus for separating a mixture of substances, at least one of which is a liquid. The most volatile component boils first and is condensed back to a liquid in the water-cooled condenser, from which it flows into the receiving flask. If a solution of salt and water is distilled, for example, the more volatile component, pure water, collects in the receiving flask, while the salt remains in the distillation flask.

Mixtures of two or more liquids with different boiling points can be separated with a more complex distillation apparatus. One example is the refining of crude petroleum into a range of useful products: aviation fuel, gasoline, kerosene, diesel fuel, and lubricating oil in the approximate order of decreasing volatility.

Another example is the distillation of alcoholic spirits such as brandy or whiskey. This relatively simple procedure caused more than a few headaches for federal authorities in the s during the era of Prohibition, when illegal stills proliferated in remote regions of the United States.

Filtration is any mechanical, physical or biological operation that separates solids from fluids liquids or gases by adding a medium through which only the fluid can pass. The fluid that passes through is called the filtrate. All alternatives should be considered with no resolution at this stage. A starting activity could be observing the burning of a candle and discussing the changes that take place.

Here the distinction can be made between the melting of the wax and the appearance of new materials. Questions posed could include:. Activities which provide problems to be explored and challenge existing ideas are useful in encouraging students to seek new explanations for things they observe. Students should investigate a number of changes and ask questions similar to those above. In all of these students should be encouraged to observe the changes that take place and to identify what products are formed.

Discussion can also centre on how these are different from the starting materials. Some examples could include:. Other activities can involve chocolate making. There are many other similar chemical changes that can be investigated - further cooking activities can include: making a chocolate cake, melting and browning cheese, making honeycomb, baking bread, poaching eggs and making toast. Other changes can include the setting of two component glues like Araldite and mixing steel wool and a solution of copper sulfate available from plant nurseries.

Oxygen is a very important reactant in many chemical reactions and students can investigate changes involving this component of air. It is important at this stage to clarify and consolidate what students have observed and to focus on what happens in a chemical reaction which is different from melting, boiling and freezing. To achieve this students could be asked in groups to make mini posters which show the changes that take place in the one or more of the reactions they have seen, particularly comparing the products with the starting materials and demonstrating how they are different.

Students then present their posters to the class. Resulting class discussion should bring out student ideas, examine alternatives and move to more accepted scientific views about chemical reactions. Activities should be carried out which test the usefulness of the chemical reactions model and further consolidate student ideas about what constitutes a chemical reaction. Students can be further encouraged to compare the products with the starting materials.

To further develop students' appreciation of the role of chemical change in their lives, they could research the production of metals from ores such as aluminium and steel or the production of plastics and synthetic fibres. The emphasis in this exploration is on the importance of chemical change in producing the materials we use every day.