chemistry homework
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1chemistry.docxHomework #3 UDC GEN CHEM 111 Name: _________________________________
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#22 Argon effuses through an apparatus at the rate of 475 mL/hr. An unknown gas effuses from the same apparatus at a rate of 453 mL/hour. What is the molecular weight of the unknown. [6]
_______________
#23 Kr effuses through an apparatus at a rate of 230.0 mL/hour. A sample of gas is one of the following: ClO, ClO2 or Cl2O. The gas effuses through the same apparatus at a rate of 261.1 mL/hour. What is the unknown gas? [7]
_______________
#24 An 850 mL sample of gas at 3.2 atm and 125 oC has a mass of 7.63 g. Use the density of the gas to determine the molecular weight of the gas. [8]
_______________
#25 An uknown gas occupies 225 mL at -10 oC and 1620 mm Hg. The sample weighs 2.642 g. Use the density to determine the molecular weight of the gas. [8]
________________
#26 Complete the following table [2/]
|
Atomic Number |
# of electrons |
Isotopic Mass |
Symbol of Isotope |
|
11 |
|
23 |
|
|
54 |
|
129 |
|
|
6 |
|
13 |
|
|
|
48 |
110 |
|
|
|
23 |
48 |
|
|
|
|
|
56Ni |
|
|
|
|
25Al |
|
|
|
|
76Se |
#27 Complete the following table [4/]
|
Compound |
Name |
|
Compound |
Name |
|
NaCl |
|
|
Na2S |
|
|
BBr3 |
|
|
PCl5 |
|
|
CaF2 |
|
|
Li2O |
|
|
NO2 |
|
|
ICl3 |
|
|
Al2O3 |
|
|
SeO2 |
|
|
Ba3N2 |
|
|
GeI4 |
|
#28 How many atoms are there in 15.35 g of Mg? [5] ______________________
#29 How much does 4.85 x 1019 atoms of Iodine weigh? [6] ______________________
#30 Calculate the mass of the number of moles of the element indicated [3/]
|
Element |
Zn |
Mo |
W |
Cs |
|
Number of moles |
1.35 mol |
0.877 mol |
3.75 mmol |
8.97 mol |
|
Mass |
|
|
|
|
#31 Convert the following sentences into chemical equations. [15]
Two molecules of hydrogen chloride react with potassium oxide to make two moles of potassium chloride and one molecule of water.
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Two atoms of potassium react with a molecule of iodine to make 2 molecules of potassium iodide.
One mole of selenium reacts with one mole of magnesium to make one mole of magnesium selenide
#32 Complete the following table. Name [5], Formula [4], Molecular weight[3]
|
Formula |
Name |
Mol Weight g/mol |
|
Formula |
Name |
Mol weight g/mol |
|
HF |
|
|
|
|
Sodium bromide |
|
|
Al2O3 |
|
|
|
|
Silicon dioxide |
|
|
PF3 |
|
|
|
|
Selenium dibromide |
|
|
CaI2 |
|
|
|
|
Dinitorogen trioxide |
|
|
BBr3 |
|
|
|
|
Phosphorous pentoxide |
|
#33 Write a number on the line to balance the equation. For this exercise you must write in the number 1. [2/]
_____ Na + _____ F2 _____ NaF _____ N2 + _____ H2 _____ NH3
_____ KCl + _____ I2 _____ KI + _____ Cl2 _____ Ga + _____ O2 _____ Ga2O3
_____ Sn + _____ I2 _____ SnI4 _____ C + _____ S8 _____CS2
_____ Ca + _____P4 _____Ca3P2 _____ I2 + _____ Cl2 _____ ICl3
