20 Questions
What is the physical quantity that represents the relationship between shear stress and velocity gradient?
Viscosity
What unit is used to measure viscosity in the SI system?
Pascal-second
What is the effect of increasing temperature on the viscosity of a fluid?
It decreases the viscosity
What is the purpose of preheating highly viscous liquids?
To facilitate their flow through tubes
What is the term used to describe the density of a substance relative to that of water?
Relative density
What is the typical range of relative density values for flammable liquids?
Less than 1
What is the purpose of expressing the density of a substance relative to that of air or water?
To make the value dimensionless
What is the term used to describe the mass of a substance per unit volume?
Mass density
What is the effect of increasing the viscosity of a fluid on the flow of bubbles through it?
It decreases the flow of bubbles
What is the characteristic of liquids that allows them to take the shape of their container?
Fluidity
What type of vapors tend to accumulate in low-lying areas?
More dense than air
What is the primary factor that determines a liquid's vapor pressure?
Volatility
What is the unit of measurement for latent heat?
Energy per unit mass
What is the definition of heat of combustion?
Heat released per unit mass of a substance during combustion
What is the primary characteristic of unstable or reactive materials?
They decompose or react with changes in temperature or pressure
What happens to a material during a phase change?
It absorbs energy
What is the relationship between volatility and vapor pressure?
Higher volatility corresponds to higher vapor pressure
What is the purpose of measuring vapor pressure?
To express a liquid's volatility
What is the definition of latent heat of fusion?
Energy absorbed during a phase change from solid to liquid
What is the definition of latent heat of vaporization?
Energy absorbed during a phase change from liquid to gas
Study Notes
Viscosity
- Viscosity is the relationship between the shear stress (force acting tangentially on a surface, divided by the surface area) and the velocity gradient perpendicular to the shear plane.
- Measured in SI units as pascal-seconds (Pa·s).
- Associated with a fluid's resistance to flow, with less viscous liquids flowing better.
- More viscous liquids have a greater resistance to bubble flow towards the surface.
Density
- Density is the mass of a sample or body divided by its volume.
- Mass-specific density is a property specific to a substance.
- Density relative to water is used to express the density of liquids and gases, and is defined as the density of a body divided by the density of water.
- For gases, density relative to air is used, and is defined as the density of a portion of the gas divided by the density of air.
- Density relative is a dimensionless value.
- Liquids with a density relative less than 1 will float on water.
Vapor Pressure
- Vapor pressure is the pressure exerted by a substance or mixture at a given temperature in a system containing only the vapor and the condensed phase (liquid or solid) of the substance or mixture.
- Vapor pressure expresses the volatility of a liquid, with more volatile liquids having higher vapor pressures.
Heat of Combustion
- Heat of combustion is the heat emitted by the complete combustion of a unit of mass.
Latent Heat
- Latent heat is the energy required for a given mass of material to change phase (melting or vaporization), or the energy released when a given mass of material changes phase (solidification or condensation).
- Expressed in units of energy per unit of mass.
Unstable or Reactive Materials
- Unstable or reactive materials are those that, in their pure state or in commercial specifications, can become self-reactive and decompose, polymerize, or explode due to changes in temperature, pressure, or mechanical shock during storage or transportation.
Learn about viscosity, its measurement in pascal-seconds, and its relation to fluid resistance and flow. Discover how it affects the flow of liquids and the movement of bubbles.
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