Welcome to ChemE Students!

ChemEStudent Energy Balances, Fluid Mechanics, General Chemistry, General Engineering, Heat Transfer, Material Balances, Organic Chemistry, Thermodynamics Leave a Comment

Welcome to ChemE Students! Your ideal website for challenging and educational engineering questions focused in Chemical Engineering. On ChemE Students, you will find daily questions, with complete hints, formulas and solutions, all for FREE!.

In the near future, we will also introduce new exciting features for our premium members, including a full question bank to help with your studying. To thank you for becoming an early adopter of ChemE Students, we have set up a special page just for you. Complete the instructions found here to be eligible for a 75% discount on our premium membership when available!

We are still under development, so most features will not be complete. We have provided three example questions (with solutions) which will be similar to our future questions. If you wish to contact us, please click here.

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ChemEStudentWelcome to ChemE Students!

Understanding the Ideal Gas Law

ChemEStudent General Chemistry Leave a Comment

An ideal gas is contained in a hot closed rigid cylinder. If the gas is further compressed, what will happen to the temperature of this gas?

A) Increases B) Remains the Same
C) Decreases D) Impossible to Predict
Use the ideal gas law to understand the relationship between the variables. No need to use actual numbers.

Ideal Gas Law:
PV=nRT

 

Solution

ChemEStudentUnderstanding the Ideal Gas Law

Filling a Leaking Tank

ChemEStudent Material Balances Leave a Comment

A 1000ft3 tank is being filled with water at a rate of 1.04 L/min. How long (seconds) will it take to half fill the tank if there is a leak rate of 4.10 ml/s?

A) 1.07*106 s B) 2.14*106 s
C) 1.34*104 s D) 3.88*104 s
This problem can easily be solved through a mass balance on the tank. In this scenario there are no generation or consumption of the water, thus reducing the conservation of mass formula to:

Accumulation = Input - Output

This question also involves the proper conversion of units. Visit the formula tab for conversion factors.

Conservation of mass formula:
Accumulation = Input + Generation - Output - Consumption 1ft^3=28.317L
 

Solution

ChemEStudentFilling a Leaking Tank

Excess Reactants

ChemEStudent General Chemistry Leave a Comment

Ammonia and Oxygen gas can be reacted together to form Nitric Oxide and Water as shown:
4NH3 + 5O2 = 4NO + 6H2O

If 100kg/day of Ammonia and 200kg/day of Oxygen gas are fed into a reactor, what is the percentage by which the excess reactant is in excess?

Use the following molecular weights:
17g/mol NH3
32g/mol O2

A) 50% B) 34%
C) 18% D) 15%
Use the molecular weight of each reactant to convert mass to moles. Using the stoichiometric relationship given by the chemical reaction, find the theoretical amount of reactant needed to complete the reaction.
To convert mass into moles: moles=mass/molecular weight
To calculate excess: excess=(fed-reacted)/fed
 

Solution

ChemEStudentExcess Reactants