Quiz 1

What are the three tips for success when dealing with sig figs?

1. When adding numbers, first put them in the same notation 2. Use pemdas 3. Identify exact numbers (like when dividing during averaging)

Significance of zeros in a number depends on location; if zeros are infant of nonzero digits? i.e. : 0.892; 0.00008

not significant

Significance of zeros in a number depends on location; If there are multiple zeros to the left of a decimal and point is NOT there? i.e.: 200 000 ; explain answer

not significant because you don't know the first number for sure; that's your guess. The zero is just a place holder; it's not a measured value OR an estimation, so therefore it's not significant and a place holder.

What are key factors in good observations?

observations shouldn't be biased; numbers aren't biased. Scientists use standardized units and similar techniques so to get consistent and similar results.

What are quantitative observations?

observations that are made with instruments such as rulers, balances, graduated cylinders, beakers, and thermometers. These results are measurable. They are exact facts

What are qualitative observations?

observations which use your senses to observe the results. (Sight, smell, touch, taste and hear.)

What is precision?

the closeness of a set of measurements of the same quantity made in the same way; precise values are close to one another but not necessarily to accepted value.

What is accuracy?

the closeness of measurements to the correct or accepted value of the quantity measured; measured accurate values are close to accepted value

What is chemistry?

the study of matter and structure and how it changes; *** the study of matter, what it's made of (composition) how it's arranged (structure), and how and why it changes (behavior)***

Why are significant figures used?

they are used in chemistry to accurately report the precision of a measurement

Why are measurements used?

they are used to describe matter and situations using numbers. They give reference and definite facts, taking out opinions.

Explain how you would determine the significant figures in a number.

If the number is NOT measured, then it's an exact number, meaning sig figs are not taken into account. An example of an exact number is the number of fingers on your hands. If it is measured, then it's considered an estimated value. Here, sig figs are taken into account

What are significant figures?

In a measurement, they consist of all the digits known with certainty plus one final digit, which is somewhat uncertain or is estimated; insignificant digits are never reported.

**What does the number of significant figures tell you about a measurement?

In any measurement, the number of significant figures is critical. The number of significant figures is the number of digits believed to be correct by the person doing the measuring. It includes one estimated digit.

What is the SI system? Describe the units too, their abbreviates and quantities they measure.

International System of Units, a revised version of the metric system that was internationally agreed as the standard measurement system. There are 7 base units, 5 of which are relevant to Chemistry; these 5 are Kilogram (for mass; kg), Meter (for length; m), Second (for time; s), Kelvin (for temperature; K), and the Mole (for amount of substance; i.e. atoms; mol).

Why is Chemistry important?

It's important because it's everything around us. Chemistry helps improve quality of live, advance society, and explain many things that happen around us that seem to be unexplainable.

What are the key prefixes?

Most commonly used and needed to memorize are kilo, centi, mili, micro, and nano. Use notecard for this :)

Why was the SI system developed?

Scientists use the SI system so to get consistent and similar results that can be easily compared.

Significance of zeros in a number depends on location; if zeros are at the end of a number and to the right of decimal point? i.e.: 57.00; 2.000 000

Significant

Significance of zeros in a number depends on location; if zeros are between nonzero digits? i.e.: 50.3; 3.0025

Significant

Significance of zeros in a number depends on location; If there are multiple zeros to the left of a decimal and point is there? i.e.: 200 000. explain answer

Significant because you are guessing to the whole. you know the 2 and the number of zeros for sure, but what you don't know is whether it is 200 000.0 or 200 000.001, for example. So you round to the whole. you are guessing to the whole.

What makes metric units easy to use?

They are all based on multiples of 10, thus one can convert between units easily.

Why are observations made?

They give us information which we can use to build things and solve important problems. They make experiments replicable.

SF: What happens if the number has no zeros?

all digits shown are significant

What are proper measurement techniques?

Having all certain information plus one estimate, include units when recording, and read the bottom of the meniscus when measuring

Describe the process of adding and subtracting with significant figures

Follow the acronym of AAR; Align Add and Round. When adding or subtracting sig figs you want to first align them to each other by decimal point placement. Then, you add or subtract, and finally you DON'T round according to sig figs. You round according to the least number of decimal places in measured values. REMEMBER THAT EXACT VALUES DON'T LIMIT OUR CALCULATIONS.1

Describe the process of multiplying and dividing with significant figures

Follow the acronym of CCR; Calculate Count and Round. When multiplying or diving sig figs you want to first make your calculation; multiply or divide. Then, depending on the least number of sig figs in the measurements involved, you will round to that same number of sig figs. 11.1 • 2.0= 22.2 BUT you round to 22 because the least number of sig figs was 2 in 2.0

What is the difference between derived units and base units?

All derived units are based off of the base units; they are typically used for measurements such as volume, density and pressure. i.e.: volume (cm^3) and area (m^2). You can always trace back the equation for the derived units to a base unit. other examples include a pascal (pa; pressure) and a watt (W; power)

Why is the SI system used?

Because not only is it easy to use due to its simplicity and ease but it consists if a logical system of units of measurements built on seven base units

What do you do when there's an error in measurement?

Errors are found especially when measuring with rulers, balances, and graduated cylinders; there are some times where the value measured might be questionable and so in order to express that, you would include a plus or minus value to express the range.