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Elements, compounds, molecules.
Properties of matter
Transfer of heat
Mixtures
Random
100
Is H2 an element or a compound?
Element
100
Draw a diagram to show the arrangement of atoms in a gas and a solid.
Your diagram should show the atoms very close together in a solid, and less atoms spread very far apart in the gas.
100
Compare the amount of energy atoms in a solid have compared to atoms in a gas.
Atoms in a solid have less energy than in a gas. They will vibrate in place. Whereas the atoms in a gas have a lot more kinetic energy and are constantly and quickly moving.
100
Mixture or chemical reaction? Making a sandwich
Mixture. Nothing 'new' is made. All elements you put in the sandwich are still there and have their same properties.
100
Draw a labeled diagram of an atom.
You should show the nucleus in the center, protons and neutrons in the center and electrons around the outside.
200
H2O - a compound? element?
Compound - it has more than one type of atom (Hydrogen and Oxygen)
200
Define the terms volume and density.
Volume is the amount of space an object takes up. Density is a measure of how compact an object is - how many atoms are squashed into the volume of the object and how large/heavy those atoms are.
200
Compare and contrast conduction and convection.
Similarities: they both involve the transfer of heat from a warm area to a cooler area. Differences: Conduction is heat transfer in a solid and convection is heat transfer in a gas or a liquid. Conduction transfers heat through direct contact between the particles. Convection involves the movement of particles rather than the direct contact between them.
200
Mixture or chemical reaction? Making a cup of coffee with sugar and milk.
Mixture - the coffee is still there, the water is there, you can see the color of the milk in the coffee and you can taste the sugar. Nothing new is made - everything still has the same properties as before.
200
Name a liquid that is LESS dense than water.
Oil (or anything else that floats on water)
300
CH4 - a molecule? element? compound?
A molecule AND a compound. It is made of more than one atom (so it is a group of atoms = molecule). It has more than one TYPE of atom = compound.
300
Explain how you would find the volume of an IRREGULARLY shaped object.
Water displacement method: Take a measured amount of water in a cylinder then add the object to the cylinder and measure the final volume of the water. Final volume - initial volume of the water = the volume of the object. (the amount the volume of the water changes by is the volume of the object).
300
Describe what happens to the molecules when ice melts
Initially the ice is solid so that molecules do not have much kinetic energy and are vibrating. As heat is added the molecules in the ice gain energy and start vibrating more vigorously. Eventually the molecules gain enough energy to break the forces that are holding them in position and start being able to move more freely like a liquid.
300
Mixture or chemical reaction? Completely burning a piece of bread in the toaster.
Chemical reaction. The black charcoal that is made is a new product. It does not look, feel, smell or taste the same as the original bread.
300
Draw a diagram to show a sea breeze is an example of a convection current.
Your diagram should show (depending on whether it is day or night and you don't need to specify) either: the air over the land being heated and rising. As the air over the land rises, the cooler air above the ocean will 'blow in' and take its place. The warm air above the land will blow out towards the ocean. The opposite: The air over the ocean being heated and rising. As the air rises over the ocean the cooler air above the land will blow out and take its place. The warm air blows from the ocean toward the land.
400
C - an atom or molecule? element or compound?
This is an atom (it only has one C) and an element (only one type of atom).
400
a)An object has a mass of 50kg and a volume of 10m3, calculate the density of the object. b) what are the units of density?
density = mass / volume = 50kg / 10m3 = 5kg/m3 Units = kg/m3
400
A candle is burning and the melted wax runs down the side of the candle and drips onto the table. a) Describe what happens as the candle wax freezes on the table. b) what happens to the air molecules immediately next to the freezing candle wax?
a)Liquid candle wax molecules have kinetic energy which allows them to move freely around and past each other. As the wax moves away from the flame it starts losing energy to the air surrounding it and the molecules start to slow down. Eventually the molecules lose enough energy to the air that they stop being able to move and can only vibrate in place = frozen. b) as the wax loses energy to the air molecules, the air molecules GAIN that energy and will move a little faster. So the air temperature next to the candle wax will increase a little due to the energy absorbed.
400
Explain the difference between a mixture and a chemical reaction.
A mixture is a group of substances that occupy the same space at the same time. No atoms are rearranged - no new product is made. The properties of the individual substances does not change. In a chemical reaction molecules in the reactants get broken apart and reconnect to each other in different ways to form completely new products. The new products have different properties and are not like the initial reactants at all. This is usually not reversible.
400
Why does a can of diet soda float in water while a can of regular soda sinks?
Diet soda has less/no sugar in it so it is LESS dense and floats. Regular soda has the same volume (the cans are the same size) but lots of sugar so it is MORE dense and sinks.
500
How many atoms are in the smallest molecule possible?
2 A molecule has to have more than one atom so the smallest molecule would have 2 atoms.
500
Water has a density of 1g/cm3. a) An object has a mass of 21g and a volume of 7cm3. Would this object float or sink in water? Why? b) Describe two different ways to change the density of the water. Make sure you also explain how the density would change (would it increase or decrease) and why.
a) 21/7 = 3g/cm3 the object is MORE dense than water so it would sink. b) If you add salt to the water the density of the water would increase (because there are more particles present in the volume of water) If you heated the water the density of the water would DECREASE. The heat would cause the water molecules to gain energy and move further away from each other - meaning less molecules in the same space.
500
Wiping sweat off with a towel does not allow sweat to do its job. You must let it evaporate. Explain this statement and why sweat must be allowed to evaporate.
When we sweat the heat from our skin/body is absorbed by the sweat drops. The energy from our skin or body is transferred to the sweat molecules causing them to gain kinetic energy until such point as they change from a liquid to a gas. As the sweat gains energy, the skin or body loses energy and so the temperature of the skin or body drops cooling us down. If a person wipes away the sweat there is nothing on the skin to absorb the energy and therefore the skin will not be cooled by the sweat.
500
Explain how the paper chromatography worked to separate the mixture of black ink in the crayola marker.
Water is the medium that carries the particles of black ink up the chromatography paper. The mixture of ink contains particles of different colors that are different sizes. The large particles move more slowly up the paper and the smaller particles are able to move more quickly up the paper. Therefore the particles are separated according to their size - the colors that travel the biggest distance are smaller than the ones that travel the smallest distance.
500
What celebration day is it tomorrow?
St Patrick's day - wear green!