Chemistry 101- Midterm Study Questions

What is the main difference between an element and a compound?

A compound contains at least two types of atoms, whereas an element contains only one type of atom.

Is a sample of water found in nature (such as from a river) a compound or a mixture?

A mixture because it has impurities and other substances present that can be separated out.

Why do chemists "count by weighing" when counting elements and compounds?

Elements and compounds are so small that they are incredibly difficult to count.

In chemistry, what is a mole?

6.022×10e23, a number of something (like dozen or pair), the number of carbon atoms in 12.01 g of carbon

The boiling of water is a what?

physical change because the gaseous water is chemically the same as the liquid.

Consider an aqueous solution in which you have dissolved 3 moles of potassium carbonate in water. How many moles of ions are in solution?

9

How many total atoms are present in 10.0 grams aluminum chloride? (molar mass AlCl3=133.3 g/mol)

1.81xe23 atoms

An ion is formed when what happens?

by either adding or taking away electrons from the atom.

Which of the following statements is true? The iron atom is best considered to be a solid. The mercury atom is best considered to be a liquid. The helium atom is best considered to be a gas. At least two of the above statements are correct. None of the above statements are correct

none

A certain ion has a charge of 2+ and 27 electrons. Which ion is it?

Cu2+

A hydrocarbon (a compound consisting solely of carbon and hydrogen) is found to be 25% hydrogen by mass. What is the empirical formula of the hydrocarbon?

CH4

Consider equal mole samples of dinitrogen monoxide, aluminum nitrate, and potassium cyanide. Rank these from the least to most number of nitrogen atoms in each sample.

potassium cyanide, dinitrogen monoxide, aluminum nitrate

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what is Dalton's theory?

all matter is made up of atoms, atoms of the same element are the same and atoms of different elements are different, atoms are indestructible, chemical reactions are rearrangements of atoms, you can break the atom, compounds are combinations of atoms

isotope

atoms with the same number of protons but different number of neutrons

Where are electrons located?

outside the nucleus

Where are protons and neutrons found?

nucleus

what is the relative mass and charge of an electron

1 and 1-

what is the relative mass and charge of a proton

1836 and 1+

what is the relative mass and charge of a neutron

1839 an d none

Charge of Silver (Ag)

+1

Charge of Aluminum (Al)

+3

is the cation named first and the anion second?

yes

for example, Fe3+ is what Fe2+ is what

ferric and ferrous

-ic is the higher charge -ous is the lower charge

yes

mono di tri tetra penta hexa hepta octa

prefixes - 1,2,3,4,5,6,7,8

P - pressure T - temperature

not additive

V - volume N - moles

additive

average mass of one H atom

1.008 amu

volume vs. moles

example of balloons: pressure is same inside and outside

pressure vs. moles

increase, increase

pressure vs. volume

decrease, increase (inverse)

volume vs. temperature

decrease, decrease

volume vs. moles

increase, increase

what is the kinetic molecular theory?

gases are made of particles in constant random motion (exerting pressure), temperature is a measure of random kinetic energy, pressure is due to collisions of gas particles with the container

daltons law of partial pressure

the total pressure exerted is the sum of the pressures that each gas would exert if it were alone, affected by number of moles

when finding the partial pressure.... rigid piston

rigid - volume is constant piston - pressure is constant