CHEM 105 - Flashcards

CH1 - Is CO₂ a pure substance or a mixture? Element or compound / homogeneous or heterogenous?

Pure substance, compound.

CH1 - What is a tentative interpretation or explanation of an observation?

A hypothesis

CH1 - Which statement best explains the difference between a law and a theory?

1. A law is truth; a theory is mere speculation.

2. A law summarizes a series of related observations; a theory gives the underlying reasons for them.

3. A theory describes what nature does; a law describes why nature does it.

2. A law summarizes a series of related observations; a theory gives the underlying reasons for them

CH1 - What does crystalline mean? How does it compare to amorphous? Examples? And vice versa

Crystalline describes a solid in which atoms, molecules, or ions are arranged in patterns with long-range, repeating order (ex. table salt, diamond); Amorphous describes a solid in which atoms or molecules do not have any long-range order (ex. glass, plastic).

CH1 - How do we classify pure substances? Mixtures? Examples?

Pure substances can be elements or compounds (H₂O, O₂, Li); mixtures can be homo- or heterogeneous (milk, soup)

CH1 - Define chemistry

the science that seeks to understand the behavior of matter by studying the behavior of atoms and molecules

CH1 - Define matter. How do we classify matter?

Anything that has mass and occupies space. Solid, liquid, gas (for now…) OR pure substance/mixture

CH1 - Define atoms & molecules

Atoms: the building blocks of molecules, organic or inorganic origin

Molecules: species that contain atoms connected in a specific geometrical arrangement

CH1 - What determines properties of matter?

The atoms and molecules within it

CH1 - What is a pure substance? What is a mixture?

PS: matter of invariable composition (elements/compounds, 1 kind)

M: matter of variable composition (several different kinds)

CH1 - What is an element?

A substance that cannot be broken down into simpler substances by chemical means (and don’t say wHaT aBoUt FiSsIoN)

CH1 - What is a compound?

a substances composed of atoms of two or more elements joined together by a chemical bond, TWO DIFFERENT

CH1 - Difference between a molecule and a compound?

Molecules are any 2+ atoms joined together, compounds are any VARYING 2+ atoms joined together. Compounds have to have 2+ different elements. Ex. H₂ is a molecule and not a compound. H₂O is a molecule and a compound

CH1 - What is homo- vs heterogeneous?

Both are ways to classify mixtures:

Homo: multicomponent substances that are uniformly distributed (miscible) ex. MILK

Hetero: multicomponent substances that are not uniformly distributed (not miscible) ex. SOUP

CH1 - Classify the following as a pure substance or mixture, then element/compound or homo/heterogeneous:

1. Pacific Oregon Chai Tea

2. Carbon Monoxide (CO) gas

3. Copper (Cu) wire

4. simple syrup

5. ice water

1. Chai: mixture, homo

2. CO: pure substance, compound

3. Cu: pure substance, element

4. syrup: mixture, homo

5. ice water: pure substance, compound

CH1 - How are scientific measurements reported in regards to sig figs?

Scientific measurements are reported so that every digit is certain except the last, which is estimated.

CH1 - Where do we draw the line when reporting volume measurements of liquids with a meniscus?

At the bottom of the U (ex. photo would be ~20, or a measurement just below IDK why 19 is above and 21 is below LOLZ)

CH1 - What are exact numbers? Example?

numbers with no uncertainty, ex. 3 distinct objects (like 3 kids even if one is an amputee)

CH1 - How many sig figs do numbers coming from counting discrete objects have? Ex. 7 pennies

Unlimited

CH1 - When are sig figs ambiguous?

When trailing zeroes are before an implied decimal point (ex. 21,000)

CH1 - What are the rules around sig figs when multiplying/dividing?

Final answer must have the lowest number of sig figs, don’t round intermediate calculations

CH1 - What are the rules around sig figs when adding/subtracting?

Final answer must have lowest number of decimal places, don’t round intermediate calculations

CH1 - What does 5.349 round to?

5.3 no relay rounding

CH1 - What is accuracy vs precision?

Accuracy refers to how close the measured value is to the actual value. Precision refers to how close a series of measurements are to one another or how reproducible they are.

CH1 - What is random error?

error that has equal probability of being too high or too low. Random error can, with enough trials, average itself out.

CH1 - What is systematic error?

error that tends to repeatedly be either too high or too low. In contrast to random error, systematic error does not average out with repeated trials.