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Grade 12Physical Chemistry

when a reaction of unknow metal bromide with hydrochloric acid takes place it gives metal chloride and HBr
if specific heat of metal=0.878 joule/gm and weight of metalchloride is 1.0gm then find the weight of metal?

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9 Years agoGrade 12
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ApprovedApproved Tutor Answer1 Year ago

To determine the weight of the unknown metal when it reacts with hydrochloric acid, we can use the information provided about the specific heat of the metal and the weight of the metal chloride produced. Let's break this down step by step.

Understanding the Reaction

When a metal bromide reacts with hydrochloric acid, it produces a metal chloride and hydrogen bromide (HBr). The general reaction can be represented as:

  • Metal Bromide + Hydrochloric Acid → Metal Chloride + HBr

In this case, we know the weight of the metal chloride produced is 1.0 g. Our goal is to find the weight of the metal that reacted.

Using Molar Mass and Stoichiometry

To find the weight of the metal, we need to consider the stoichiometry of the reaction. The metal chloride formed will have a specific molar mass based on the metal and chlorine. However, since we don't know the exact metal, we can still use the specific heat and the weight of the metal chloride to derive the weight of the metal.

Applying the Specific Heat Formula

The specific heat of the metal is given as 0.878 joules/gm. This value indicates how much energy is required to raise the temperature of 1 gram of the metal by 1 degree Celsius. However, in this context, we can use it to relate the heat absorbed or released during the reaction to the mass of the metal.

Setting Up the Calculation

We can use the relationship between the weight of the metal chloride and the weight of the metal. The metal chloride is formed from the metal and chlorine. Assuming the metal chloride is of the form MCl, where M is the metal, we can express the weight of the metal chloride as:

  • Weight of Metal Chloride (MCl) = Weight of Metal (M) + Weight of Chlorine (Cl)

Given that the weight of the metal chloride is 1.0 g, we can denote the weight of the metal as W. The weight of chlorine in the chloride can be calculated based on its molar mass (approximately 35.5 g/mol). Thus, we can express the relationship as:

  • 1.0 g = W + (35.5 g/mol × n)

Where n is the number of moles of chlorine that reacted. Since we are looking for the weight of the metal, we can rearrange this equation to solve for W.

Finding the Weight of the Metal

Assuming that the metal chloride is a simple binary compound (MCl), we can simplify our calculations. The molar mass of the metal chloride can be approximated as:

  • Molar Mass of MCl = Molar Mass of Metal (M) + 35.5 g/mol

Since we know the total weight of the metal chloride is 1.0 g, we can express this as:

  • 1.0 g = M + 35.5 g/mol

However, without the specific molar mass of the metal, we cannot directly calculate W. But we can assume that the weight of the metal will be significantly less than 1.0 g, given that it combines with chlorine to form the chloride.

Final Calculation

For simplicity, if we assume the metal has a molar mass similar to common metals (like sodium, potassium, etc.), we can estimate the weight of the metal. If we take a hypothetical metal with a molar mass of around 23 g/mol (like sodium), we can set up the equation:

  • 1.0 g = W + 35.5 g/mol

Solving for W gives us:

  • W = 1.0 g - 35.5 g/mol

This indicates that the weight of the metal is likely to be very small, and we would need the specific molar mass of the metal to get an exact figure. However, based on typical values, we can estimate that the weight of the metal is likely around 0.5 g or less, depending on the specific metal involved.

In summary, while we can set up the equations and understand the relationships, the exact weight of the metal requires knowledge of its molar mass. If you have any specific metal in mind, we can refine this calculation further!