Chemistry

Water is life


Water is an essential substance for the life of organisms on earth. It is found in large quantities in all living things. In the human body, 71% of our weight is water.

There is 85% water in our blood, 80% in the brain, 70% in the skin and 30% in our bones. In vegetables, the amount of water is higher. See the table below.

VEGETABLE

QUANTITY IN% OF WATER

CABBAGE

90

CARROT

88

APPLE

84

CORN / BEAN

15

TOMATO

95

LETTUCE

94

STRAWBERRY

89

POTATO

77

It is in water that transformations occur because substances are dissolved in water in our bodies. Water transports and distributes blood to the rest of the body.

We lose water through urine, sweat, feces and exhalation. All the water that is eliminated will be missed later on by our body, so the importance of replacing this water and the importance of feeling thirsty. An adult should drink about 2.5L of water per day.

LOSS OF WATER DAILY (AVERAGE)

DAILY LOSS

AMOUNT IN cm³

URINE

1250

SWEAT

650

EXPIRATION

500

Feces

100

TOTAL

2500 cm³ = 2.5L

If the amount of water we drink does not make up for the amount lost, then the body becomes dehydrated, causing damage to health.

The amount of water we lose depends on organism to organism, each environment or situation. On hot days we lose more water than on cold days. Those who practice more physical activities lose more water than those who stand still.

In plants, the roots remove from the soil the raw sap that is a solution of water and minerals. In the leaves, this sap performs photosynthesis. Photosynthesis is the phenomenon that occurs in the presence of light, where the plant transforms carbon dioxide (CO2) and water into glucose and oxygen.

Still in the leaves, the substances formed from photosynthesis, join with the water forming the elaborate sap. The elaborate sap returns to the other parts of the plant. It is stored as starch and cellulose.

- Domestic use:

  • Drinking (human consumption)
  • Baths and personal hygiene
  • Flush toilets and home cleaning

- Industrial use:

  • Beverage Manufacturing
  • Medicine Manufacturing
  • Perfume and cosmetics manufacturing

- Navigation and transport:

  • Tourists for tours
  • Small and big loads
  • Passengers in transit
  • Ocean liners
  • Oil tankers

Electricity

The electrical energy that comes from the hydroelectric plants is a result of the water force. Hydroelectric plants use the energy of moving water to obtain electricity. To build a dam it is necessary to dam the water of a river.

The dammed water is piped and driven at high speed to the turbines (metal vane wheels) that begin to spin. This movement is transmitted to another part, the generator, turning the energy of water into electrical energy.

In Brazil, there are several hydroelectric plants, among them one of the largest in the world: Itaipu, in Paraná. The São Francisco River, here in Brazil, is also used to provide electricity. Along its course there are the plants of Três Marias, Paulo Afonso, Itaparica, Moxotó and Sobradinho.

Not all countries have large rivers and waterfalls, such as Brazil. Only a few countries have great hydroelectric potential, such as the USA, Russia, China and Canada.