Question

What is the effect on chemical properties and physical properties of water when temperature is changed? (a) Chemical properties of water remain same but the physical state changes with change in temperature. (b) Chemical properties of water change with change in temperature but physical properties remain same. (c) Thereisnoeffectonchemicalorphysicalproperties of water when temperature is changed. (d) Both chemical and physical properties of water change with change in temperature.

Short answer

(a) Chemical properties of water remain same but the physical state changes with change in temperature.

Step-by-step solution

Understand the Difference Between Chemical and Physical Properties

Chemical properties refer to the characteristics that dictate how a substance will react with other substances, essentially determining its composition and reactivity. Physical properties, on the other hand, are the characteristics that can be observed or measured without changing the substance’s chemical identity. These include boiling point, melting point, density, and state of matter.

Effect of Temperature Change on Physical Properties

When the temperature of water changes, its physical state can change; it can turn into ice upon freezing, remain liquid at room temperature, or become gas when boiling. Therefore, the physical properties such as state of matter, density, and temperature-dependant solubility are affected by the temperature change.

Effect of Temperature Change on Chemical Properties

The chemical properties of water, such as its ability to act as a solvent and participate in chemical reactions like hydrolysis, remain unchanged when its temperature changes. The composition of water (H2O) remains the same in all physical states.

Select the Correct Option

Based on our understanding, the correct option is that chemical properties of water remain the same, but the physical properties can change with temperature. Hence, the physical state of water changes (solid, liquid, gas), but not its chemical properties.

Key concepts

Chemical Properties

Water is a substance with unique chemical properties that sustain life on Earth. One of its fundamental chemical characteristics is its stable molecular composition of two hydrogen atoms bonded to an oxygen atom, recognized as H2O. This composition does not change with temperature variations.

In terms of its reactivity, water is known for being a universal solvent. This means it can dissolve a vast array of substances, which is essential for biological and chemical processes. Water participates in chemical reactions like hydrolysis, where it breaks down compounds by reacting with them. Even when heated or frozen, water retains these chemical properties, enabling it to facilitate reactions regardless of its physical state.

Physical Properties

Different from its chemical properties, the physical properties of water are sensitive to temperature changes. Water's most readily observed physical properties include its melting point at 0°C, boiling point at 100°C, density, viscosity, and surface tension. As the temperature of water increases, molecules gain energy and move faster, causing water to expand and become less dense. This is why ice floats on liquid water.

Surface tension decreases with temperature, affecting the way water interacts with other substances and itself—something that plays a crucial role in biological systems and the environment. The unusual characteristic of water expanding upon freezing leads to ice having a lower density than liquid water—a property critical to aquatic life survival in cold climates.

Temperature Change Effect

When water undergoes a temperature change, it can transition between its three states: solid, liquid, and gas. These phase changes are physical and don't alter water's chemical structure.

Cooling water leads to ice formation as molecular motion decreases and a structured lattice forms. This is known as freezing. Conversely, heating water increases molecular motion, potentially creating enough energy to break intermolecular bonds and transition water from liquid to gas in a process named evaporation. When this occurs rapidly at the surface, it's called boiling. These processes demonstrate how temperature is a driving force changing the state of water and affecting its physical properties significantly, without altering its chemical identity.

State of Matter

Water's ability to exist in different states of matter—solid (ice), liquid (water), and gas (water vapor)—is an extraordinary physical property influenced by temperature.

Each state has its own set of physical characteristics. Ice, the solid state of water, has a definite shape and volume, while liquid water takes the shape of its container and maintains a consistent volume. Water vapor, the gaseous state, neither has a fixed shape nor a fixed volume, expanding to fill its container. These changes in state are a physical process that impact ecosystems, weather patterns, and the environment at large, illustrating the profound effect temperature has on the physical behaviors of water.