KADAR ZAT DALAM CAMPURAN DAN KADAR UNSUR DALAM SENYAWA : KIMIA SMA KELAS 10

Summary

This video explains the methods for determining the concentration of substances in mixtures and compounds. It covers three key concepts: mass percentage, volume percentage, and parts per million (PPM). The video includes detailed examples for each concept, demonstrating how to calculate the percentage of a substance in a mixture, such as finding the mass percentage of magnesium oxide in a mixture of materials, or determining the volume of alcohol in a beverage. It also explores how to calculate the percentage of elements like carbon, hydrogen, and oxygen in a compound like glucose.

Takeaways

• 😀 Mass percentage (percent by mass) is the ratio of the mass of a substance in a mixture to the total mass of the mixture, multiplied by 100%. Example: The percentage mass of magnesium oxide (MgO) in a mixture of materials was calculated as 11.11%.
• 😀 Volume percentage (percent by volume) represents the volume of a substance in a mixture per 100 units of the total volume. For instance, the volume percentage of alcohol in a solution was found to be 41.67%.
• 😀 Parts per million (PPM) is used to express the concentration of a substance in a very dilute mixture. For example, the concentration of chlorine in water (from a PDAM sample) was calculated to be 3 PPM.
• 😀 The formula for determining the mass percentage of a substance in a mixture is: (Mass of substance / Total mass of mixture) * 100%.
• 😀 To calculate the mass of a substance from the percentage, the formula is rearranged to: Mass of substance = (Percentage / 100) * Total mass of mixture.
• 😀 To calculate volume percentage, the formula is: (Volume of substance in mixture / Total volume of mixture) * 100%.
• 😀 For very dilute solutions, PPM is calculated by: (Mass of substance in mixture / Total mass of mixture) * 10^6.
• 😀 When determining the mass of a substance in a solution, knowing the density and volume of the solution is key. The formula for mass is: Mass = Density * Volume.
• 😀 When calculating the composition of compounds like glucose (C6H12O6), the mass percentages of elements like carbon, hydrogen, and oxygen are determined based on their atomic masses and molecular structure.
• 😀 For calculating the mass percentage of elements in a compound, the formula is: (Index of element * Atomic mass of element) / Molecular mass of the compound * 100%. This formula was applied to calculate the percentage of carbon, hydrogen, and oxygen in glucose.

Q & A

What is meant by the percentage mass of a substance in a mixture?

The percentage mass of a substance in a mixture represents the mass of that substance in 100 grams of the mixture. It can be calculated by dividing the mass of the substance by the total mass of the mixture and multiplying by 100.

How do you calculate the percentage mass of MgO in a mixture?

To calculate the percentage mass of MgO in a mixture, first determine the total mass of the mixture by adding the masses of all components. Then, divide the mass of MgO by the total mass and multiply by 100 to get the percentage.

What is the formula for calculating the percentage by volume of a substance in a mixture?

The percentage by volume is calculated by dividing the volume of the substance by the total volume of the mixture and multiplying by 100.

How do you calculate the mass of NaOH in a solution with a given percentage mass?

To calculate the mass of NaOH in a solution, use the formula: mass of NaOH = percentage mass × total mass of the solution / 100. For example, for a 20% NaOH solution and a total mass of 500 grams, the mass of NaOH would be 100 grams.

What does the unit 'ppm' stand for, and when is it used?

PPM stands for 'parts per million' and is used to measure the concentration of a substance in a solution or mixture, especially when the amount is very small. It represents the number of parts of a substance in one million parts of the total mixture.

How do you calculate the concentration of chlorine in water using ppm?

To calculate the concentration of chlorine in water in ppm, first determine the mass of chlorine and the total mass of water. Then, use the formula: concentration in ppm = (mass of chlorine / mass of water) × 10^6.

What is the formula for calculating the percentage of an element in a compound?

The formula for calculating the percentage of an element in a compound is: percentage of element = (atomic mass of the element × number of atoms of the element / molecular mass of the compound) × 100.

How do you find the percentage mass of carbon in glucose (C6H12O6)?

To find the percentage mass of carbon in glucose, first calculate the molecular mass of glucose (C6H12O6). Then, multiply the atomic mass of carbon by 6 (the number of carbon atoms) and divide by the total molecular mass of glucose. Multiply by 100 to get the percentage.

What is the total molecular mass of glucose (C6H12O6)?

The molecular mass of glucose is calculated by adding the masses of all atoms: (6 × 12 for carbon) + (12 × 1 for hydrogen) + (6 × 16 for oxygen), which equals 180 g/mol.

How do you calculate the percentage of hydrogen in glucose?

To calculate the percentage of hydrogen in glucose, multiply the atomic mass of hydrogen by 12 (the number of hydrogen atoms) and divide by the total molecular mass of glucose (180 g/mol). Then, multiply by 100 to get the percentage, which is 6.7%.