chemistry
two substances that react to form rust
iron and oxygen
What other factors help rust form quickly
oxygen and moisture
Which of the following observations is the best evidence that a chemical reaction is taking place?
a) an open flame appears
b) A liquid changes to gas
c) An object changes volume
d) A solid disappears into a liquid
a) an open flame appears
are cations positive or negative? are anions positive or negative?
cations - positive
anions - negative
endothermic
absorbing heat
define corrosion
Corrosion is the breakdown of a metal as it reacts with chemicals in the environment
What is the ph of the following substances?
Lemon juice
milk magnesia
borax
Lemon juice - 2
Milk magnesia - 10
Borax - 9
Define buffering capacity
ability of a solution to resist changes in its pH
Non metallic elements form anions while metallic elements form cations - true or false
TRUE
amylase
digestive enzyme
Some skin creams claim that they are pH balanced yet do not have a Ph of 7 - why?
If a substance is neutral, it does not means that the substance will have a balanced pH. pH balanced means that the pH of the substance (cream) will not vary much or easily.
Classify the following solutions as highly acidic, slightly acidic, neutral, slightly basic, or highly basic
A solution w a pH of 13
Solution w pH of 6
Solution w pH of 1
The moisture on ur skin
A solution w a pH of 13 - highly basic
Solution w pH of 6 - neutral
Solution w pH of 1 - highly acidic
The moisture on ur skin - slightly acidic
Rain is naturally acidic. Under what conditions does normal rain become acidic rain
Rain usually becomes acidic rain because of air pollution.
Name at least four substances that are carried by the circulatory system
Oxygen, blood, carbon dioxide, nutrients, hormones
Define the difference between corrosion and rusting
Corrosion is the process by which certain materials, metals and non-metals, deteriorate as a result of oxidation. Rusting is oxidation of iron in the presence of air and moisture. Corrosion can occur on materials such as ceramics or polymers. Rusting occurs on surfaces of iron and its alloys.
Define acid precipitation
any form of precipitation with acidic components, such as sulfuric or nitric acid that fall to the ground from the atmosphere in wet or dry forms. This can include rain, snow, fog, hail or even dust that is acidic
What two groups of compounds are largely responsible for causing acid precipitation
Sulfur dioxide and nitrogen oxides
Describe the function of the circulatory system
Move nutrients and gasses to all of the cells of the body and to carry away wastes through the bloodstream
Explain why you can save money on home heating fuel if you keep gas furnace clean and operating at peak efffiecieny
A clean furnace operating at peak efficiency implies that maximum amount of fuel is completely burned to generate heat rather than being wasted as carbon monoxide and unburnt fuel. These products of incomplete combustion do not only affect the consumption of the fuel but are also atmospheric pollutants.
Describe the ph changes expected if an acid is used to neutralize a base with pH 12
The pH of the base is 12. As acid is added to the flask containing the base, the ph of the solution decreases gradually until it reaches 7. This point is the point of neutralization
the combustion of hydrocarbons sometimes produces a yellow flame and a sooty residue. Describe the conditions when this might occur?
Hydrocarbons produce a yellow flame and a sooty residue when they are burnt in insufficient supply of air. Because of the insufficient supply of air (oxygen) the hydrocarbon fails to burn completely and yields carbon monoxide responsible for the yellow flame and unburnt hydrocarbon that appears as the sooty residue.
How is cardiac muscle different from the smooth muscle that surrounds the digestive tract?
Cardiac muscle pumps blood. Smooth muscle controls blood pressure in vessels and helps to move food through the digestive tract.