If a different chemical reaction produced 125 milliliters of hydrogen gas from 40 grams of a metal reacting with an excess of HCl at standard temperature and pressure (STP), what would be the molar concentration of HCl?
To find the molar concentration of HCl, we can use the given information about the volume of hydrogen gas produced and the mass of metal consumed in the reaction. Here are the steps to calculate the molar concentration:
Step 1: Convert grams to moles for the metal used in the reaction.
To do this, we need to know the molar mass of the metal. Let's assume the molar mass of the metal is M grams/mol. We can use the given mass of the metal (40 grams) and the molar mass to find the number of moles of the metal.
Number of moles of metal = Mass of metal (in grams) / Molar mass of metal
Step 2: Convert volume of hydrogen gas to moles.
The volume of hydrogen gas produced is given as 125 milliliters. To convert this volume to moles, we need to use the ideal gas law.
PV = nRT
At STP (Standard Temperature and Pressure), the values are as follows:
P = 1 atm (atmosphere)
T = 273.15 K (Kelvin)
R = 0.0821 L·atm/mol·K (ideal gas constant)
Since the volume is given in milliliters, we need to convert it to liters by dividing by 1000.
Volume of hydrogen gas (in liters) = 125 milliliters / 1000 = 0.125 liters
Using the ideal gas law, we can calculate the number of moles of hydrogen gas produced.
n = PV / RT
Substituting the values, we get:
n = (1 atm) * (0.125 L) / (0.0821 L·atm/mol·K * 273.15 K)
Step 3: Determine the molar ratio between HCl and metal in the reaction.
The balanced chemical equation for the reaction between the metal and HCl will provide the stoichiometric relationship between the two reactants. Let's assume the equation is:
Metal + x HCl ⟶ y Hydrogen gas
The stoichiometric coefficient 'y' represents the number of moles of hydrogen gas produced for 'x' moles of HCl.
Step 4: Calculate the number of moles of HCl.
Since we know the molar ratio between HCl and hydrogen gas, we can use the equation:
Number of moles of HCl = (Number of moles of hydrogen gas) / y
Step 5: Calculate the molar concentration of HCl.
Finally, we can find the molar concentration of HCl by dividing the number of moles of HCl by the volume of the HCl solution used in the reaction.
Molar concentration (c) = (Number of moles of HCl) / Volume of HCl solution (in liters)
By following these steps and performing the necessary calculations, you should be able to find the molar concentration of HCl.