In the complex world of oil and gas, understanding chemical reactions and material properties is essential. One key concept that aids in this understanding is Equivalent Weight (EW).
What is Equivalent Weight?
Equivalent weight, also known as gram equivalent weight, is a measure of the reactive capacity of a substance. It represents the atomic or formula weight of a material divided by its valence or the number of electrons it gains or loses in a chemical reaction.
How is Equivalent Weight Calculated?
The formula for calculating equivalent weight is:
EW = Molecular Weight / Valency
Example:
Consider Sodium Hydroxide (NaOH). Its molecular weight is 40 g/mol. In a reaction, NaOH releases one hydroxide ion (OH-) with a charge of -1. Therefore, its valency is 1.
EW of NaOH = 40 g/mol / 1 = 40 g/equivalent
Why is Equivalent Weight Important in Oil & Gas?
Equivalent weight plays a crucial role in several aspects of oil and gas operations:
Summary
Equivalent weight is a crucial concept in oil and gas chemistry. It simplifies the understanding of chemical reactions by providing a measure of a substance's reactive capacity. Its application extends to various aspects of oil and gas operations, from optimizing chemical treatments to characterizing reservoir properties. By understanding this fundamental concept, professionals can make informed decisions that lead to efficient and safe operations.
Instructions: Choose the best answer for each question.
1. What does Equivalent Weight (EW) measure?
a) The mass of a substance b) The density of a substance c) The reactive capacity of a substance d) The boiling point of a substance
c) The reactive capacity of a substance
2. How is Equivalent Weight calculated?
a) EW = Molecular Weight / Valency b) EW = Valency / Molecular Weight c) EW = Atomic Mass / Density d) EW = Density / Atomic Mass
a) EW = Molecular Weight / Valency
3. What is the Equivalent Weight of Calcium Chloride (CaCl2) if its molecular weight is 111 g/mol and its valency is 2?
a) 55.5 g/equivalent b) 111 g/equivalent c) 222 g/equivalent d) 166.5 g/equivalent
a) 55.5 g/equivalent
4. How is Equivalent Weight used in corrosion control?
a) To determine the amount of corrosion inhibitor needed b) To measure the rate of corrosion c) To identify the type of corrosion d) To prevent metal fatigue
a) To determine the amount of corrosion inhibitor needed
5. Which of the following is NOT an application of Equivalent Weight in oil & gas operations?
a) Chemical reactions b) Reservoir characterization c) Pipeline design d) Water treatment
c) Pipeline design
Task:
You are working on an acidizing operation to stimulate a well. The formation rock contains calcium carbonate (CaCO3) with a molecular weight of 100 g/mol. The acid used is hydrochloric acid (HCl) with a molecular weight of 36.5 g/mol. Calculate the equivalent weight of both substances and determine the mass of HCl required to completely react with 1000 g of CaCO3.
Hint: Remember that the valency of CaCO3 is 2 and the valency of HCl is 1.
**1. Calculate Equivalent Weight:** - **CaCO3:** EW = Molecular Weight / Valency = 100 g/mol / 2 = 50 g/equivalent - **HCl:** EW = Molecular Weight / Valency = 36.5 g/mol / 1 = 36.5 g/equivalent **2. Determine mass of HCl needed:** - The reaction between CaCO3 and HCl is a 1:2 ratio (1 mole of CaCO3 reacts with 2 moles of HCl). - Since the equivalent weight represents the mass of 1 equivalent, we can use the ratio of equivalent weights to find the required mass of HCl. - Mass of HCl = (EW of CaCO3 / EW of HCl) * Mass of CaCO3 = (50 g/equivalent / 36.5 g/equivalent) * 1000 g = 1369.86 g **Therefore, you would need approximately 1369.86 g of HCl to completely react with 1000 g of CaCO3.**
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