This does not mean that hydrogen and oxygen always combine in a 2:1 ratio to form H
2 O. Multiple proportions are possible. For example, hydrogen and oxygen may combine in different proportions to form H
2 O
2 rather than H
2 O. In H
2 O
2 , the H:O ratio is 1:1 and the mass ratio of hydrogen to oxygen is 1:16. This will be the same for any molecule of hydrogen peroxide.
Volume relationships in gases
In a chemical reaction between gases, the relative volumes of the gases in the reaction are present in a ratio of small whole numbers if all the gases are at the same temperature and pressure. This relationship is also known as
Gay-Lussac's Law .
For example, in the reaction between hydrogen and oxygen to produce water, two volumes of H
2 react with 1 volume of O
2 to produce 2 volumes of H
2 O.
2H
2 + O
2
2H
2 O
In the reaction to produce ammonia, one volume of nitrogen gas reacts with three volumes of hydrogen gas to produce two volumes of ammonia gas.
N
2
3H
2
2NH
3
This relationship will also be true for all other chemical reactions.
Summary
The following video provides a summary of the concepts covered in this chapter.
Matter does not stay the same. It may undergo physical or chemical changes.
A
physical change means that the form of matter may change, but not its identity. For example, when water evaporates, the energy and the arrangement of water molecules will change, but not the structure of the water molecules themselves.
During a physical change, the
arrangement of particles may change but the mass, number of atoms and number of molecules will stay the same.
Physical changes involve small changes in
energy and are easily reversible.
A chemical change occurs when one or more substances change into other materials. A chemical reaction involves the formation of new substances with
different properties . For example, magnesium and oxygen react to form magnesium oxide (MgO)
A chemical change may involve a
decomposition or
synthesis reaction. During chemical change, the mass and number of atoms is conserved, but the number of molecules is not always the same.
Chemical reactions involve larger changes in energy. During a reaction, energy is needed to break bonds in the reactants and energy is released when new products form. If the energy released is greater than the energy absorbed, then the reaction is exothermic. If the energy released is less than the energy absorbed, then the reaction is endothermic. Chemical reactions are not easily reversible.
Decomposition reactions are usually
endothermic and synthesis reactions are usually
exothermic .
The
law of conservation of mass states that the total mass of all the substances taking part in a chemical reaction is conserved and the number of atoms of each element in the reaction does not change when a new product is formed.
The
conservation of energy principle states that energy cannot be created or destroyed, it can only change from one form to another.
The
law of constant composition states that in any particular compound, all samples of that compound will be made up of the same elements in the same proportion or ratio.
Gay-Lussac's Law states that in a chemical reaction between gases, the relative volumes of the gases in the reaction are present in a ratio of small whole numbers if all the gases are at the same temperature and pressure.
Summary exercise
Complete the following table by saying whether each of the descriptions is an example of a physical or chemical change:
Description
Physical or chemical
hot and cold water mix together
milk turns sour
a car starts to rust
food digests in the stomach
alcohol disappears when it is placed on your skin
warming food in a microwave
separating sand and gravel
fireworks exploding
For each of the following reactions, say whether it is an example of a synthesis or decomposition reaction:
(NH
4 )
2 CO
3
2NH
3 + CO
2 + H
2 O
4Fe + 3O
2
2Fe
2 O
3
N
2 (g) + 3H
2 (g)
2NH
3
CaCO
3 (s)
CaO + CO
2
For the following equation:
CaCO
3
CO
2 + CaO
show that the 'law of conservation of mass' applies.
Communication is effective because it allows individuals to share ideas, thoughts, and information with others.
effective communication can lead to improved outcomes in various settings, including personal relationships, business environments, and educational settings. By communicating effectively, individuals can negotiate effectively, solve problems collaboratively, and work towards common goals.
it starts up serve and return practice/assessments.it helps find voice talking therapy also assessments through relaxed conversation.
miss
Every time someone flushes a toilet in the apartment building, the person begins to jumb back automatically after hearing the flush, before the water temperature changes. Identify the types of learning, if it is classical conditioning identify the NS, UCS, CS and CR. If it is operant conditioning, identify the type of consequence positive reinforcement, negative reinforcement or punishment
nature is an hereditary factor while nurture is an environmental factor which constitute an individual personality. so if an individual's parent has a deviant behavior and was also brought up in an deviant environment, observation of the behavior and the inborn trait we make the individual deviant.
Samuel
I am taking this course because I am hoping that I could somehow learn more about my chosen field of interest and due to the fact that being a PsyD really ignites my passion as an individual the more I hope to learn about developing and literally explore the complexity of my critical thinking skills
hello. autism is a umbrella term. autistic kids have different disorder overlapping. for example. a kid may show symptoms of ADHD and also learning disabilities.
before treatment please make sure the kid doesn't have physical disabilities like hearing..vision..speech problem. sometimes these
Jharna
continue..
sometimes due to these physical problems..the diagnosis may be misdiagnosed.
treatment for autism.
well it depends on the severity.
since autistic kids have problems in communicating and adopting to the environment.. it's best to expose the child in situations where the child
Jharna
child interact with other kids under doc supervision.
play therapy.
speech therapy.
Engaging in different activities that activate most parts of the brain.. like drawing..painting. matching color board game.
string and beads game.
the more you interact with the child the more effective
Jharna
results you'll get..
please consult a therapist to know what suits best on your child.
and last as a parent. I know sometimes it's overwhelming to guide a special kid.
but trust the process and be strong and patient as a parent.
Jharna
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