General Chemistry 1

A typical aspirin, C$_9$H$_8$O$_4$ , tablet contains 0.36 g. How many molecules are present?

A sample of 45.8 g of MgSO$_4$ $\cdot$ 4 H$_2$O contains how many moles of MgSO$_4$ $\cdot$ 4 H$_2$O ?

How many moles of sodium ions, Na$^{+}$, are there in 5.63 g of Na$_2$SO$_4$ ? (molar mass of Na$_2$SO$_4$ = 124.04 g/mol)

How many grams of silver are in 0.263 mol of Ag??

How many moles of nitrogen atoms are in 15.0 g of N$_2$O$_5$ (calculate with molar mass of N$_2$O$_5$ = 108.010 g/mol) ?

One of the compounds of iron and oxygen occurs naturally in the mineral magnetite. When a 2.447 g sample was analyzed it was found to have 1.771 g of Fe. Calculate the empirical formula of this compound.

A white powder used in paints, enamels and ceramics has the following percentage composition: Ba (69.6%), C (6.09%), and O (24.3%). What is the empirical formula?

Given a molar mass of 116.24 g/mol and an empirical formula of C$_3$H$_8$N, find the molecular formula for this compound.

Calculate the mass percentages of the elements in CO$_2$

A sample of a liquid with a mass of 8.657 g was decomposed into its elements and gave 5.217 g of C, 0.9620 g of H and 2.478 g of O. What is the percentage composition of each element in this compound?

What is the formula for the following hydrate:

3.71 g Na$_2$CO$_3$ , 6.29 g H$_2$O

Stupidium is a fictional element with 2 isotopes, $^35$St with a mass of 34.9567 g/mol, and $^39$St with a mass of 39.0095 g/mol. The molar mass of St is 35.9826 g/mol. What are the percent abundances of the isotopes?

Naturally occurring boron is composed of 19.8% of $^{10}$B and 80.2% of $^{11}$B. Atoms of $^{10}$B have a mass of of 10.0129 u and those of $^{11}$B have a mass of 11.0093 u. Calculate the average atomic mass of boron.

The nuclear power industry extracts $^6$Li but not $^7$Li from natural samples of lithium. As a result, the average molar mass of commercial samples of lithium is increased. The current abundace of the two isotopes are 7.42% and 95.58% respectively, and the masses of their atoms are 9.968 x 10$^{-24}$ g and 1.165 x 10$^{-23}$ g. What is the current molar mass of a natural sample of lithium?

N$_2$ + 3 H$_2$ $\longrightarrow$ 2 NH$_3$

How many grams of hydrogen are needed to produce 68 g of ammonia? (molar mass of NH$_3$ = 12.031 g/mol, the molar mass of H$_2$ = 2.015 g/mol)

2 Al + Fe$_2$O$_3$ $\longrightarrow$ Al$_2$O$_3$ + 2 Fe

An operation requires at least 86.0 g of Fe to be produced. What is the minimum mass in grams of Fe$_2$O$_3$ necessary to produce the desired amount of products? How much Al$_2$O$_3$ is produced as a side product?

MM of Fe$_2$O$_3$ = 159.489 g/mol

MM of Al$_2$O$_3$ = 101.961 g/mol

H$_2$SO$_4$ + 2 KOH $\longrightarrow$ 2 H$_2$O + K$_2$SO$_4$

How many moles of KOH are requred to make 3.0 moles of K$_2$SO$_4$ ?

N$_2$ + 3 H$_2$ $\longrightarrow$ 2 NH$_3$

If 5 moles of N$_2$ react with excess H$_2$ how many moles of NH$_3$ will the reaction yield?

N$_2$ + 3 H$_2$ $\longrightarrow$ 2 NH$_3$

If 5.0 grams of N$_2$ react with excess H$_2$ how many grams of NH$_3$ will the reaction yield?

2 Na + Cl$_2$ $\longrightarrow$ 2 NaCl

How many grams of Cl$_2$ are needed to react completely with 12.0 g of Na?