Problem 2 - Chemistry: Principles and Reactions

Question

Classify each of the following as element, compound, or mixture. (a) gold (b) milk (c) sugar (d) vinaigrette dressing with herbs

Step-by-Step Solution

Answer

Question: Classify the following substances as an element, compound, or mixture: a) Gold, b) Milk, c) Sugar, d) Vinaigrette dressing with herbs. Answer: a) Gold is an element, b) Milk is a mixture, c) Sugar is a compound, d) Vinaigrette dressing with herbs is a mixture.

Step 1: Classify gold (a)

Gold consists of only one type of atom, "Au." Therefore, gold is an element.

Step 2: Classify milk (b)

Milk is a combination of proteins, carbohydrates, fats, vitamins, and minerals, not chemically bonded and retaining their individual properties. Therefore, milk is a mixture.

Step 3: Classify sugar (c)

Sugar, a carbohydrate, is made from carbon, hydrogen, and oxygen atoms chemically bonded together in a fixed composition ratio. Therefore, sugar is a compound.

Step 4: Classify vinaigrette dressing with herbs (d)

Vinaigrette dressing with herbs is a combination of various ingredients, like vinegar, oil, and herbs, not chemically bonded and retaining their individual properties. Therefore, vinaigrette dressing with herbs is a mixture.

Key Concepts

Understanding Elements

Elements are the basic building blocks of matter. They consist of only one type of atom and cannot be broken down into a simpler substance by chemical means. Each element has its own unique properties, such as boiling and melting points, density, and ability to conduct electricity and heat.

Gold, as classified in the exercise, is an excellent example of an element. It is represented by the symbol 'Au' from the periodic table and is composed entirely of gold atoms. The idea that an element consists only of one type of atom is crucial for understanding chemical reactions and the composition of compounds and mixtures.

• Elements are substances made of only one type of atom.
• They have unique physical and chemical properties.
• The periodic table is a systematic arrangement of all known elements.

Decoding Compounds

Compounds are pure substances that are made up of two or more different types of atoms that are chemically bonded together. The atoms in compounds are present in fixed ratios that determine the compound's formula. For example, water (H2O) is a compound consisting of two hydrogen atoms bonded to one oxygen atom.

Sugar, or sucrose, is a compound made of carbon (C), hydrogen (H), and oxygen (O) atoms. The specific ratio and bonding of these atoms give sugar its distinct sweet taste and physical characteristics.

• Compounds are composed of two or more different types of atoms bonded together.
• They have a fixed composition represented by a chemical formula.
• Chemical bonds in compounds can be broken down through chemical reactions to form new substances.

Mixtures Explained

Mixtures are a combination of two or more substances that are physically blended together, without any chemical bonding. Each substance in a mixture retains its own chemical properties. Mixtures can be homogeneous, where the components are evenly distributed (like salt water), or heterogeneous, where the components are unevenly distributed (like vinaigrette dressing).

Take milk, it is a mixture because it contains water, fat, proteins, and other nutrients mixed together without any chemical bonds between them. Similarly, vinaigrette is a mixture of oil, vinegar, and herbs, and each component retains its individual properties.

• Mixtures contain two or more substances physically combined.
• The components of a mixture do not have a fixed ratio and can vary.
• Mixtures can be separated into their individual substances through physical methods.