Chemistry Bell ringer 2

How many milligrams of phosphorus- 32 remain after 57.2 days if you start with 4.0 mg of the isotope?

.25

Calculate the amount of moles in 56.0 g of magnesium hydroxide.

.960 moles of Mg(OH)2

What is the limiting reactant?

1 chocolate square

Calculate the number of molecules in 0.045 moles of nitrogen monoxide.

2.7 x 10^22

How many formula units are in 4.564 moles of Al2(SO4)3 ?

2.748 X 10^24

What is the percent composition of phosphorus in H3PO4?

31.61% P

Calculate the Energy of violet light with a frequency of 7.50 X 10-14

4.97 x 10-47

What is the mass # of an atom which contains 28 protons, 28 electrons, and 34 neutrons?

62

Calculate the mass of 0.75 moles of lithium sulfate

82 g Li2SO4

The element Mg has 12 protons. Mg+2, a magnesium ion, has how many electrons?

C. 10

Which substance has chemical properties similar to those of radioactive 235U?

C. 233U

Two nitrogen combined with four fluorine would make this compound.

Dinitrogen tetrafluoride N2F4

Which equation is balanced?

A. 2H2 + O2 → 2H2O

Which atom contains exactly 15 protons?

A. P - 32

How many moles of water are in the following equation? 2H2 + O2 → 2H2O?

B. 2

How many electrons are found in the outer shell of the group 2 alkaline metals?

B. 2 electrons

Write the formula for copper (II) chloride

CuCl2

Which of the following is NOT an isotope?

D. O

Name the compound that 2 hydrogen and 1 oxygen produces?

Dihydrogen Monoxide WATER

Write the formula for Manganese IV oxide

MnO2