Chemistry Final

All of the following are in aqueous solution. Which is incorrectly named?

HCN, cyanic acid

Which among the following represent a set of isotopes. Atomic nuclei containing I. 20 protons and 20 neutrons II. 21 protons and 19 neutrons III. 22 protons and 18 neutrons IV. 20 protons and 22 neutrons V. 21 protons and 20 neutrons

I, IV and II, V

A solution is also called a

homogenous mixture

wPCL5 + xH20 = yPOCl3 + zHcl The equation is properly balanced when:

w=1, x=1, y=1, z=2

If the Thompson model of the atom had been correct, Rutherford would have observed:

Alpha particles going through the foil with little or no deflection

In balancing an equation, we change the __________ to make the number of atoms on each side of the equation balance.

coefficients of compounds

NaHCO3 is the active ingredient in baking soda. How many grams of oxygen are in 0.52g of NaHCO3?

0.30g

A sample of ammonia has a mass of 43.5 g. How many molecules are in this sample?

1.54 x 10^24 molecules

What is the molar mass of cyrolite (Na3AlF6)?

104.2 g/mol

How many of the following postulates of Dalton's atomic theory are still scientifically accepted? I. All atoms of the same element are identical II. Atoms are indestructible III. Compounds are combinations of different atoms IV. A chemical reaction changes the way atoms are grouped together

2

Bromine exists naturally as a mixture of bromine-79 and bromine-81 isotopes. An atom of bromine-79 contains

35 p, 44 n, 35 e

What is the molar mass of ethanol (C2H5OH)?

46.07 g/mol

A substance contains 35.0g nitrogen, 5.05g hydrogen, and 60.0g of oxygen. How many grams of hydrogen are there in a 153g sample of this substance?

7.72g

An element consists of two isotopes of masses 69.95 amu and 71.95 amu with abundances of 25.7% and 74.3% respectively. What is the average atomic mass of this element?

71.4 amu

How many atoms of hydrogen are present in 7.63g of ammonia?

8.09 x 10^23

A hydrocarbon (a compound consisting solely of carbon and hydrogen) is found to be 85.6% carbon by mass. What is the empirical formula for this compound?

CH2

You are given a compound with the formula MCl2, in which M is a metal. You are told that the metal ion has 26 electrons. What is the identity of the metal?

Ni

The scientist whose alpha-particle scattering experiment led him to conclude that the nucleus of an atom contains a dense center of positive charge is

Rutherford

Naturally occurring element X exists in the three isotopic forms: X-28 (27.977 amu, 92.23% abundance), X-29 (28.976 amu, 4.67% abundance), and X-30 (29.974 amu, 3.10% abundance). What is the identity of element X?

Si

You have a sample of zinc (Zn) and a sample of aluminum (Al). You have an equal number of atoms in each sample. Which of the following statements concerning the masses of the samples is true?

The mass of the zinc sample is more than twice as great as the mass of the aluminum sample

Which metals form cations with varying positive charges?

Transition metals

Examples of a pure substance are

elements, compound, pure water and carbon dioxide

An ion is formed by

adding or subtracting electrons from the atom

All the following are characteristics of nonmetals except:

appear in the upper left-hand corner of the periodic table