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3 years ago

Why do vinyl raincoats become brittle as they get old, even if they are not exposed to air or to any pollutants

Chemistry

1 answer:

Leto [7]3 years ago

6 0

Answer:

The substances made from polyvinyls are generally brittle and hard. This property prevails because the polymer strands present in the polyvinyls form a very regular and well-organized packing composition in the solid-state. The Van der Waals associations between the strands make the substance brittle. To make the substance soft and suitable to use as a raincoat, the incorporation of small molecules is done within the molten polymer before the hardening of the plastic.

These polymer strands act as plasticizers and prevent the strands of polymer from forming a hard and brittle conformation.

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Which of the following threats to biodiversity is a result of over-fishing?

LUCKY_DIMON [66]

Overfishing is an example of human impact on biodiversity.
In simple terms, overfishing means that the sea animals hunted for food ( fishes, crustaceans, mollusks etc.) in a year are hunted in numbers greater than the number of newborn individuals of that species in that year. This means that the populations of these animals do not have the time to regrow their numbers.
This results in a dramatic decline of populations of many marine animals.

5 0

3 years ago

Read 2 more answers

Consider a mixture of NaCl and NaNO3 that is 31.8% Na by mass. Calculate the percentage by mass of NaCl in the mixture.

lutik1710 [3]

<u>Answer:</u> The percentage by mass of NaCl in the mixture is 38.5 %

<u>Explanation:</u>

To calculate the mass percentage of element in compound, we use the equation:

$\text{Mass percent of element}=\frac{\text{Mass of element}}{\text{Mass of compound}}\times 100$ .......(1)

<u>For NaCl:</u>

Mass of sodium element = 23 g

Mass of NaCl = 58.5 g

Putting values in equation 1, we get:

$\text{Mass percent of sodium element}=\frac{23g}{58.5g}\times 100=39.32\%$

Mass fraction of sodium metal in NaCl = 0.3932

<u>For $NaNO_3$ :</u>

Mass of sodium element = 23 g

Mass of $NaNO_3$ = 85 g

Putting values in equation 1, we get:

$\text{Mass percent of sodium element}=\frac{23g}{85g}\times 100=27.1\%$

Mass fraction of sodium metal in sodium nitrate = 0.271

Let us assume the mass fraction of NaCl in the mixture is 'x'

So, the mass fraction of $NaNO_3$ in the mixture will be '(1-x)'

We are given:

Percent by mass of Na in the mixture = 31.8 %

Mass fraction of Na in the mixture = 0.318

Evaluating the mass fraction of NaCl in the mixture:

$[(x\times 0.3932)+((1-x)\times 0.271)]=0.318$

x = 0.385

Percent by mass of NaCl in the mixture will be = $(0.385\times 100)=38.5\%$

Hence, the percentage by mass of NaCl in the mixture is 38.5 %

4 0

3 years ago

when a compound containing c h and o is completely combusted in air what reactant besides the hydrocarbon is involved in the rea

Arada [10]

When a compound containing C, H and O is completely combusted in air what reactant besides the hydrocarbon is involved in the reaction is Oxygen.

<h3>What is hydrocarbon?</h3>

A hydrocarbon is an organic molecule composed completely of hydrogen and carbon in organic chemistry. Group 14 hydrides include hydrocarbons. Hydrocarbons are often colourless and hydrophobic, with scents that are weak or exemplified by gasoline and lighter fluid. They exist in a wide range of molecular forms and phases, including gases (like methane and propane), liquids (like hexane and benzene), low melting solids (like paraffin wax and naphthalene), and polymers (such as polyethylene and polystyrene). Hydrocarbon refers to naturally occurring petroleum, natural gas, and coal, as well as their hydrocarbon derivatives and refined forms, in the fossil fuel industry. The primary source of energy on the planet is the combustion of hydrocarbons.

To learn more about hydrocarbons visit:

brainly.com/question/17578846

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7 0

2 years ago

In a gasoline engine, the area in the cylinder head where the air-and-fuel mixture is burned is called the

Neporo4naja [7]

The answer is A, the combustion chamber.

7 0

4 years ago

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Choose the molecule or compound that exhibits dipole-dipole forces as its strongest intermolecular force.

LuckyWell [14K]

Answer:

SO2

Explanation:

Dipole-Dipole exist between parmanent dipoles in a molecule. THis means that molecule must have a parmanent dipole moment in it.

Example - HCl

Hydrogen bonding is an attraction between lone pair of an electronegative element and H atom of same or different molecule. H must be covalantly attached to either F, N or O.

Example - H2O

Among the molecules given in the list only SO2 and H2O exihibits parmanent moment. As BCl3 , CBr4 and H2 are symmetric compounds.

Since, SO2 cannot exihibit H- bonding only dipole-dipole forces as its strongest intermolecular force.

5 0

3 years ago