The valence of aluminum is +3, and the valence of chlorine is -1. The formula for aluminum chloride is correctly written as
A) $ClAl _3$.
B) $Cl _3 Al$.
C) $Al _3 Cl$.
D) $AlCl _3$.
Answer (2)
Determine the valences of aluminum (+3) and chlorine (-1).
Set up the equation 3 x + ( − 1 ) y = 0 to ensure the compound is neutral.
Solve for the smallest integer values of x and y, where x = 1 and y = 3 .
Conclude that the chemical formula for aluminum chloride is A lC l 3 .
Explanation
Understanding the Problem We are given that aluminum (Al) has a valence of +3 and chlorine (Cl) has a valence of -1. We need to determine the correct chemical formula for aluminum chloride. The chemical formula must be neutral, meaning the sum of the valences must be zero.
Setting up the Equation Let the chemical formula be A l x C l y , where x and y are the number of aluminum and chlorine atoms, respectively. The total valence is given by the equation: 3 x + ( − 1 ) y = 0 This simplifies to: 3 x = y
Solving for x and y We want the smallest integer values for x and y that satisfy the equation 3 x = y . If we let x = 1 , then we have: y = 3 ( 1 ) = 3 So, x = 1 and y = 3 .
Determining the Formula Therefore, the chemical formula for aluminum chloride is A lC l 3 .
Examples
Understanding chemical formulas is crucial in various real-life applications, such as in medicine when determining the composition of drugs, in environmental science when analyzing pollutants, and in materials science when designing new compounds with specific properties. For instance, knowing the correct formula for a medication ensures that the right amount of each element is present, which is vital for its effectiveness and safety. Similarly, in environmental monitoring, accurately determining the chemical formulas of pollutants helps in identifying their sources and devising strategies to mitigate their impact.
The formula for aluminum chloride is determined by balancing the charges from aluminum (+3 valence) and chlorine (-1 valence). The correct formula is A lC l 3 , as it contains one aluminum atom and three chlorine atoms, ensuring electrical neutrality. Therefore, the correct answer is option D: A lC l 3 .
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