Category Chemistry

Chemistry exercises
Chemistry

Chemistry exercises

In this section you will find several chemistry exercises, all with the answers. Click below on the chosen content and good studies! Chemical Kinetics Chemical Functions, Indicators, pH and Modern Theories

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Chemistry

Water

Water on planet Earth Water is found everywhere: in the seas, rivers, lakes, clouds, groundwater, in the air, animals, plants, humans. Water is indispensable for life. Hydrosphere On our planet, there is a huge layer on the surface of the earth's crust that is covered with water.
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Chemistry

What is atom and molecule?

To better understand the concept of atom and molecule, imagine that you have to split a piece of something, for example water. And then it goes on dividing, dividing and dividing… until it reaches a portion that it can no longer divide. This portion we call the molecule. Molecule - Smallest portion of a substance, containing the same composition as this substance.
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Chemistry

Physical state changes

Changes in physical states of matter are: fusion, vaporization, condensation, solidification and sublimation. In water, the most common transformations are fusion, vaporization, condensation and solidification. Following is the explanation of each one. Fusion Change from solid state to liquid.
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Chemistry

Waage

Peter Wagge was a chemist born in Flekkefjord, Norway, on June 29, 1833. Together with Guldberg, he formulated the Chemical Law of Mass Action as a function of Reagent Speed ​​and Concentration, determining whether this reaction would be reversible in terms of concentrations. of reagents. He was a professor at the University of Oslo.
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Chemistry

Water cycles

After the earth formed, its surface cooled, clouds and rain formed. From the rains the rivers, lakes, seas, oceans and groundwater formed. Clouds form by evaporating liquid water, which always returns to Earth in the form of rain, snow or hail.
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Chemistry

Water

Water on planet Earth Water is found everywhere: in the seas, in the rivers, in the lakes, in the clouds, in the groundwater, in the air, in animals, in plants, in the human being. Water is indispensable for life. Hydrosphere On our planet, there is a huge layer on the surface of the earth's crust that is covered with water.
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Chemistry

Combustion

Note the following experience. Material - 1 cup; - 2 candles; - 1 box of matches. Procedure: - light both candles; - cover one of the candles with a glass; - observe. What keeps the candle flame lit is the oxygen gas. The candle that is not covered with the glass will only go out when the wax runs out. This is because there is so much oxygen gas in the environment.
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Chemistry

Water (continued)

Home Purification When there is no water treatment network in certain localities, artesian wells are common. But to dig the well, it is necessary to choose a location away from garbage dumps, sewers, pits and livestock. The interior of the well should be lined with a semipermeable wall (brick) with its base at a height of 40cm from the floor.
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Chemistry

Diseases caused by water

Water from rivers, lakes and seas can be contaminated by various microorganisms (worms, bacteria, protozoa), eggs and larvae of disease-causing animals and may be polluted by toxic substances (cadmium and mercury, for example). This is usually caused by city sewage. Disease transmission can be achieved by ingesting contaminated or polluted water and also by using such water.
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Chemistry

Air

Our planet is surrounded by an immense layer of gases, the atmosphere. It is around the earth and is maintained through the pull of gravity. It is about 1000 km thick. Atmosphere It is the layer of air that surrounds the Earth. Some facts illustrate the existence of a space containing air from the ground: - when we breathe, we remove oxygen gas from this layer; - when an airplane takes off, it must have sufficient speed to be able to support itself in the air; - when jet aircraft at high altitudes are stabilized because they are at a level of the atmosphere where there is little turbulence.
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Chemistry

Weather forecasts

Meteorology is the science that studies weather conditions. Weather and climate are not the same thing. Time is when we talk about the weather conditions that happen at any given time. Climate deals with the most frequently occurring atmospheric conditions in a given region. Factors interfere with the weather forecast Some factors may interfere with the weather forecast: clouds, air masses, cold and hot fronts, temperature, air humidity and atmospheric pressure.
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Chemistry

Air composition

Atmospheric air is formed by various gases, water vapor, microorganisms and impurities (dust and soot). The gases in the atmosphere include oxygen, noble gases (helium, neon, argon, krypton, radon, xenon), nitrogen, and carbon dioxide. The following table shows the amount (percentage) of each gas in the atmosphere, nitrogen being the most abundant.
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Chemistry

Diseases caused by water (continued)

Yellow Fever Yellow fever is an infectious disease caused by a flavivirus (the yellow fever virus) for which a highly effective vaccine is available. The disease is transmitted by mosquitoes and occurs exclusively in Central America, South America and Africa. In Brazil, yellow fever is usually acquired when an unvaccinated person enters wild transmission areas (cerrado regions, forests).
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Chemistry

Buoyancy

It is a force exerted by water. The same force that keeps a person floating in the water also keeps a transatlantic floating in the sea. We call this force thrust. So what keeps the bodies floating in the water is the buoyancy. But this force is also present when the object, denser than water, sinks.
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Chemistry

Air

Our planet is surrounded by an immense layer of gases, the atmosphere. It is around the earth and is maintained through the pull of gravity. It is about 1000 km thick. Atmosphere It is the layer of air that surrounds the Earth. Some facts illustrate the existence of a space containing air from the ground: - when we breathe, we remove oxygen gas from this layer; - when an airplane takes off, it must have sufficient speed to be able to support itself in the air; - when jet aircraft at high altitudes are stabilized because they are at a level of the atmosphere where there is little turbulence.
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Chemistry

Function of inorganic chemistry

Some chemicals with similar properties have been grouped into chemical functions. Chemical Function - set of compounds with similar chemical properties. Inorganic substances fall into four major groups, which are known as the functions of inorganic chemistry. They are: acids, bases, oxides and salts.
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Chemistry

Diseases caused by water (continued)

Dengue Dengue is one of the biggest concerns regarding infectious diseases in Brazil today. It is a virus transmitted by a type of mosquito (Aedes aegypti) that bites only during the day, unlike the common mosquito (Culex), which bites at night. The infection can be caused by any of four types (1, 2, 3 and 4) of dengue virus, which produce the same manifestations.
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Chemistry

Function of Inorganic Chemistry (continued)

Bases Bases are all substances that produce the OH- (hydroxyl) anion in water. When a base comes in contact with water, it dissociates and releases OH-. Examples: NaOH + H 2 O ↔ Na + + OH- Mg (OH) 2 + H 2 O ↔ Mg 2+ + 2OH - Al (OH) 3 + H 2 O ↔ Al 3+ + 3OH - A base is identified by presence of OH - on the right side of the formula.
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Chemistry

Air properties

You can't catch or see the air, but we know it exists. Through its properties, it is possible to prove its existence. Air is matter and occupies the entire space of the environment in which there is no other matter. For example, in a half-water bottle, air occupies the other (upper) half of this bottle.
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Chemistry

Water as solvent

In nature, we find several types of water. We hardly find it pure. This is because, in water, various other substances are dissolved. So we can say that water is a great solvent, that is, it dissolves many other substances. It is formed by two or more pure substances. Homogeneous Mixture It consists of only one phase.
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