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56 Cards in this Set

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Chemistry

C3

Why are there gaps in the periodic table?

For undiscovered elements

Why did scientists support Mendeleev's predictions?

Because he predicted the properties of gallium and it was discovered in 1875

Which elements occur naturally on earth?

1 to 92

How are elements above 93 made?

In nuclear reactors

What are transition metals?

Typical metals

What can transition metals do?

Alter their electron arrangement to form different ions, for example Fe2+ AND Fe3+

What are transition metals useful as?

Catalysts

What are group seven elements known as?

Halogens

Why are smaller halogens more reactive than larger ones?

Because the attraction from the nucleus is bigger, so electrons are attracted to it more easily

What happens to hydrogen chloride gas when it is dissolved in water?

It becomes hydrogen and chlorine atoms which forms hydrochloric acid (because of the hydrogen ions: H+)

What causes permanent hard water?

Dissolved calcium/ magnesium sulfate, nitrate, or chloride

What causes temporary hard water?

Calcium/ magnesium hydrocarbonate

How can temporary hardness be removed?

By boiling water, which changes the hydrogen carbonate to carbonate ions and releases carbon dioxide.

How can permanent hardness be removed?

By adding sodium carbonate or passing it through an ion exchange column

How does an ion exchange column work?

It contains sodium or hydrogen ions which replace the calcium or magnesium in the water

What does hard water and soap produce?

Insoluble scum

What precipitate is achieved by adding sodium carbonate?

Calcium or magnesium carbonate

How does a water filter work?

Carbon absorbs impurities.


Ion exchange resins swap metal ions for hydrogen.


Silver nanoparticles kill microbes in the water.



How does distillation work?

Impure water is boiled, then condensed. It is expensive because boiling the water requires so much energy.

How can the energy in food be measured?

By burning the food and measuring the temperature rise it causes in water.

How are calories converted to joules?

By multiplying calories by 4.2

What happens in exothermic reactions?

Less energy is needed to make the bonds in the products than to break the bonds in the reactants, so there is "spare" energy. This is given off to the surroundings as heat.

What happens in endothermic reactions?

More energy is needed to make the bonds in the products than to break the bonds in the reactants, so the reaction requires energy. This is taken from the surroundings, therefore cooling them down.

In a methane molecule (carbon bonds to four hydrogens) which bond is the hardest to break?

The last one, the energy given for each bond is an average.

How can hydrogen gas be produced?

By electrolysing water

Is using hydrogen as a fuel more efficient in a normal car, or in the battery of an electric car?

Electric car! (60% efficient)




Normal car is only 20% efficient

What are two advantages of hydrogen fuel?


  1. No Carbon dioxide or Sulfur dioxide emissions.
  2. Releases three times as much energy as petrol per kg


What are three disadvantages of hydrogen fuel?


  1. Very explosive
  2. Much larger fuel tank
  3. Has to be stored as compressed gas

In a fuel cell, where are oxygen and hydrogen gases fed to?

Oxygen is fed to a cathode



Hydrogen is fed to an anode


.

What catalyst is used to remove the electrons from the hydrogen?

Platinum

Where do the hydrogen electrons go after being removed from the hydrogen?

Round the circuit to react with the hydrogen and oxygen to produce water

What can barium sulfate be used for?

It can be put through the body as it is insoluble, and then shows up on x-rays of soft tissue in intestines.

How many particles are in a mole?

Avogadro's number (6.02 x10 ^13)

What is concentration measured in?

moles/ dm^3

In titrations, what goes in the beaker?

Acid with known concentration plus indicator.

In a titration, what goes in the burette?

Alkali solution

In a reversible reaction, what is equilibrium?

When a reaction is going both ways at the same speed

How can the dynamic equilibrium be shifted in one direction?

By changing conditions such as temperature

How can the reaction to produce ammonia be increased in the forward direction?

By increasing the pressure

How is ammonia made?

The Haber process!

Why is ammonia production more efficient at lower temperatures?

Because it is an exothermic reaction, if the surroundings are heated then it will cause the reaction to happen in the opposite direction.

What happens to unreacted nitrogen and hydrogen in the haber process?

It is recycled

What happens in the Haber process?


  1. Methane is converted to carbon monoxide and hydrogen by steam reforming.
  2. Carbon monoxide then reacts with water to make hydrogen (using a catalyst)

Describe the efficiency of the haber process

A small amount of ammonia is produced at a very fast rate. This is more efficient than a higher amount at a slower rate.

What is formed when alcohols dissolve in water?

Neutral solutions (molecules do not form ions)

What do alcohols produce when reacted with sodium?

Sodium (prefix)oate and hydrogen.


Eg, ethanol produces sodium ethanoate.

What is produced when an alcohol is reacted with oxygen?

Carbon dioxide

What is vinegar made of?

Ethanoic acid and water

What homologous series of compounds is ethanoic acid part of?

Carboxylic acids

What is the functional group of the carboxylic acids?

-COOH

What do ethanoic acids and water produce?

Hydrogen ions, so are acidic.


(Becomes COO- and H+)



What do carboxylic acids and metal carbonates produce?

Carbon dioxide, water, and metal salt of the acid

What do alcohols and carboxylic acids produce?

Smelly compounds known as esters.

What sort of acid is a carboxylic acid when it is dissolved in water?

Weak ass acid

Top lad

Gonna slay this chemistry test