6661404
Description
Flashcards by Pranathi Poojary, updated more than 1 year ago
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Created by Pranathi Poojary
about 8 years ago
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| Question | Answer |
| Solids have particles that....? Solids have....? | are close together, vibrate along fixed means. Fixed shape, fixed volume and cannot flow. |
| Liquids have particles that....? Liquids have....? | are still close together, slide past each other. Fixed volume, take shape of the container. Can flow |
| Gases have particles that....? Gases have....? | are far apart, move randomly everywhere. No fixed shape and volume. Can flow. |
| Particles can either be...? | Ions Molecules Atoms |
| What is an ion? | An electronically charged atom. |
| What is the difference between an atom and a molecule? | An atom is the smallest particle that cannot be put into simpler forms chemically while a molecule is two or more atoms chemically combined. |
| Why does the melting and boiling points of a PURE substance always occur at a constant temperature? | Because the energy (got from either the heat or cold) is used to break the forces of attraction instead of raising the temperature. |
| Why does diffusion not take place in solids but in liquids and gases only? What diffuses faster, gases or liquids? | Particles in liquids and gases move freely while particles in solids cannot move. Gases diffuse faster because the particles are more free and move faster. |
| What diffuses faster, ammonia solution (NH3) or HCL and why? | Ammonia solution diffuses faster because it has a lower molecular mass than HCL. |
| What is the diffusion rate? | Diffusion rate is inversely proportional to the square root of its relative molecular mass. |
| What 5 methods are used to separate mixtures and when are they used? | Filtration - separating an insoulble solid from a solution Simple distillation - separating a liquid from non volatile impurities (soluble solid) Fractional distillation - separating a mixture of miscible liquids of different boiling points Chromatography - separating different components of a mixture by using their different speeds of movement Solvent extraction |
| What is residue? | The remnant after an experiment. (filtration, distillation) |
| What is the difference between simple and fractional distillation? | Simple distillation separates a soluble solid from a solution by evaporating the liquid leaving the solid behind and then condensing the liquid; fractional distillation separates a liquid from a solution of two or more miscible liquids. |
| Describe fractional distillation using a mixture of ethanol and water. | The solution is boiled. At 90 degrees, as told by the thermometer, ethanol boils. At this temperature water is a liquid and ethanol, a gas. The ethanol vapor travels up the fractionating column and is condensed and collected as a distillate while the water is left behind as a residue. |
| Describe chromatography briefly. | Chromatography is the separation of different components from a mixture by using their different speeds of movements over a medium (filter paper or chromatography paper). Capillary attraction carries the components upwards. |
| The speed at which the components, during chromatography, depends on... | The molecular mass: the lower the faster the component The attraction towards the component: the stronger the faster the component |
| What is the retention factor and how can it be used? | distance traveled by component divided by the distance traveled by the solvent front. Retention factors are compared with known materials to identify components of the mixture. |
| What is a pure substance and what is its importance? | Contains only one kind of substance and is used in medicine and the food industry. Any impurity can be fatal. |
| How is purity assessed? | By determining the boiling and melting point. Impurities increase the boiling point and lower the melting point. |
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