Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

23. Lipids

Physical Properties of Fatty Acids

GOB Chemistry

23. Lipids

Physical Properties of Fatty Acids

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3:00 minutes

Problem 78a

Textbook Question

The total kilocalories and grams of fat for some typical meals at fast-food restaurants are listed here. Calculate the number of kilocalories and the percentage of total kilocalories from fat (1 gram of fat = 9 kcal). Round kcals to the tens place.
a. a beef burrito, 470 kcal, 21 g of fat

Verified step by step guidance

Step 1: Understand the problem. You are tasked with calculating the number of kilocalories contributed by fat and the percentage of total kilocalories from fat for a beef burrito. The given data includes total kilocalories (470 kcal) and grams of fat (21 g). Additionally, 1 gram of fat provides 9 kcal.

Step 2: Calculate the kilocalories from fat. Use the formula:

kcal = grams \times 9

. Substitute the given value of 21 grams of fat into the formula.

Step 3: Round the kilocalories from fat to the tens place. This ensures the result aligns with the rounding requirement specified in the problem.

Step 4: Calculate the percentage of total kilocalories from fat. Use the formula:

percentage = \frac{kcal_fat}{kcal} \times 100

. Substitute the values for kilocalories from fat and total kilocalories (470 kcal).

Step 5: Round the percentage to the nearest whole number, as percentages are typically expressed in whole numbers for simplicity.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Kilocalories

Kilocalories (kcal) are a unit of energy commonly used to measure the energy content of food. One kilocalorie is equivalent to 1,000 calories, and it represents the amount of energy required to raise the temperature of one kilogram of water by one degree Celsius. Understanding kilocalories is essential for evaluating dietary energy intake and managing nutrition.

Fat Content

Fat content in food is typically measured in grams and indicates the amount of fat present in a serving. Since fats provide 9 kcal per gram, knowing the fat content allows for the calculation of the total energy derived from fat in a meal. This is crucial for assessing the nutritional quality of meals, especially in fast-food contexts.

Percentage of Total Kilocalories from Fat

The percentage of total kilocalories from fat is calculated by dividing the kilocalories derived from fat by the total kilocalories of the meal and multiplying by 100. This percentage helps to understand the proportion of energy coming from fat, which is important for dietary planning and health considerations, particularly in managing fat intake.

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Related Practice

Textbook Question

The total kilocalories and grams of fat for some typical meals at fast-food restaurants are listed here. Calculate the number of kilocalories and the percentage of total kilocalories from fat (1 gram of fat = 9 kcal). Round answers to the tens place.

a. a beef burrito, 470 kcal, 21 g of fat

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Textbook Question

Considering their chemical structure, why are the melting points of oils lower than those of fats?

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Textbook Question

Olive oil is a monounsaturated oil with a melting point of -6 °C. Soybean oil is a polyunsaturated oil with a melting point of -16 °C . Explain their difference in melting points.

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Textbook Question

Stearic acid and linoleic acid each have 18 carbon atoms. Why does stearic acid melt at 69 °C but linoleic acid melts at –5 °C?

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Textbook Question

Can there be any chiral carbon atoms in triacylglycerols? If so, which ones can be chiral and what determines their chirality?

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Textbook Question

Which of these fatty acids has the lower melting point? Explain why.