Chem 1 A test question first exam

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Is the temperature at which dry ice evaporates a physical or chemical property

It is a physical property because the dry ice goes from solid to a liquid. However the composition does not change.

Is apple juice a pure substance, or heterogeneous or homogeneous mixture?

homogeneous, because the juice and water are evenly uniformly distributed throughout. Juice from the top tastes the same as the bottom

What makes a mixture able to be separated by filtration?

if you are able to put it an "experiment" and separate it into it's parts. For example when mud passes through a filter it leaves the mud/ sand in the filter and the water below.

List one of the parts of Dalton's atomic theory that we now know is incorrect and state why it is now wrong

each element is composed of tiny, indestructible particles called atoms; this is false because we can split atoms and harness it's energy (nuclear power bombs)

From your text you know that three isotopes of neon exist; Ne20, Ne 21, and Ne22. Explain why the atomic mass of neon on the chart is listed as 20.179 and not something much closer to the average of 21 amu.

Because the natural abundance percentage of Ne-20 is higher than the other two.

You know that three isotopes of neon exist 20Ne, 21 Ne, and 22Ne. Explain how we can meausre the nautral abundace and the atomic mass of the Ne-21

If you know the natural abundance of Ne20 and Ne22, we would take their natural abundance and subtract that from 100, and that would be the natural abundance of Ne21. atomic mass is the average mass of the atoms isotopes weighted together

What was the unexpected observation that led rutherford to abandon the thomson model?

alpha particles were passing through the gold foil from the lead, and few of the particles were deflected through large angles.

Rutherford proposed the existence of neutrons long before they were actually found present in the nucleus. Why did he think they were required?

because the neutron was acting as a spacer and balanced the the atom because it has a 0 charge and a weight of 1.6749 × 10−27 kg.

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