Scientific Process Unit - H Chem

which expression is equal to the number of grams (g) in 2.43 kilograms (kg)

2.43 x 1000g/1kg

a teacher wants to figure out the amount of solution that is needed for a titration experiment in a class lab. the class has 15 students, and each experiment needs 50 mL of solution. if each student will perform the experiemnt two times, how many mL of solution will the teacher need for the whole class

1500 mL

a year has 365 days, and a day has 24 hours. if an hour has 60 minutes and a minute has 60 seconds, how many seconds are there in a year

3.15 x 10^7 s

zachary adds 26.45 g to 2.55 g. how many significant figures should his answer have

four

the hydrogen ion concentration of a vinegar solution is 0.00010 M. how is this concentration written in scientific notation?

1.0 x 10^-4 M

the mass of a single atom of carbon can be found by dividing the atomic mass (12.01 g) by 6.022 x 10^23. what is the mass of a single carbon atom, correctly written in scientific notation with the correct number of significant figures

1.994 x 10^-23 g

boyd takes additional measurements of the mass of product formed in a reaction. he uses a balance that has smaller graduations than the first balance he used. what is boyd most likely trying to change

he is trying to increase his precision but not his accuracy

thomas records the masses of several rocks as 7.40 g, 7.85 g, 7.60 g, and 7.40 g. what is the mode of thomas's data set

7.40

which tool was most likely used in a procedure if the lab report shows that approximately 300 mL of water was used

a beaker

what is one advantage of using a computer over a graphing calculator

computers hold larger amounts of data

the teacher prepares 2.50 liters (L) of salt soultion for a class experiment. how many quarts (qt) are in 2.50 ? (1 quart = 0.943 liters)

2.65 qt

miranda gets a small cut on her thumb after she breaks a beaker, and she begins to look around for the lab first aid kit. what important first step should she have taken

she should have first notified the teacher

a scientist wants to use a model to help present the results of his detailed scientific investigation. why would a model be useful

because the model makes the concepts easier to understand

which of these steps would most likely be part of a lab procedure

record the time to complete a chemical reaction

the independent variable is the only factor that a scientist

varies for different groups in an experiment

to test the effectiveness of a new nutrient supplement, one group of identical mice is given the supplement, and the other group is not given anything. which is the most complete list of parts of an experiment presented in this scenario

independent variable, control group, experimental group

randy observed that cooked onions in his food taste very differently from the raw onions that he had on his salad. he wondered why that was so. he thinks that he has an idea, but he is not sure. what has he developed in his mind

a hypothesis

a scientist develops a new experiment to test atomic theory. his results do not agree with the theory. what will most likely happen next

the scientist will repeat the experiment to make sure that his lab results are reliable

alyssa observed a flock of small birds in her yard. the birds visited a pair of feeders that her parents put out for them and splashed in the birdbath. which question is a nonscientific question that she might ask about the birds

are birds that visit the feeders happier than those that do not

the florida everglades are one of the most diverse ecosystems in the US and are home to many species of birds, reptiles, amphibians, and fish. recently, scientists have investigated and determined that the population of pythons, which are from asia, has increased greatly. what question is least likely to be based on these results

are the pythons a new species

a teacher describes a mathematical system that can be used to convert the weight of water to the mass of water. what is the teacher most likely describing

dimensional analysis

mrs. rushing has 3 chemistry classes with 24 students each. an experiment calls for each student to use 4 test tubes. how many test tubes are needed in all for her classes

288 test tubes

juana performs the calculation 6.05 + 3.156 + 5.0 how should she report the answer using the correct number of significant figures

14.2

what is the correct way to write 0.0000250 in scientific notation

2.50 x 10^-5

the accepted value for the density of liquid mercury is 13.5336 g/mL. four scientists measure the density of liquid mercury in their individual laboratories. the most accurate measurement is

dr. smith, who measures 13.54 g/mL

rachel is performing an acid-base titration. she hopes to determine the concentration of an unknown acid solution to two decimal places. which is the best tool to find the volume of the base that she needs to neutralize the acid

buret

yusef adds all of the values in his data set and then divides by the number of values in the set. what is yusef most likely finding

the mean

in what way would a digital thermometer be preferable to those from a liquid-based thermometer

digital thermometer readings can be more readily combined with computer software

henry plans to moniter the change in concentration of an acid during a chemical reaction. he wants to collect data ever 0.1 seconds and then to graph his data and insert it into a text document. which pair of tools would be best for henry to use

a computer and a concentration probe

which of the following values is equal to 1 micrometer

0.000001 meter

which practice poses the greatest safety concern

accumulating clutter on the lab bench

the MSDS for glacial acetic acid says that it is a flammable liquid that can severely burn any human tissue it comes in contact with. it reacts with bases, various metals, and strong oxidizing agents. its vapors can form explosive mixtures with air. based on this information, which statement is applicable to glacial acetic acid

it should be handled in a fume hood, away from open flames

in an investigation that uses the scientific method, which step immediately follows asking a question

creating a hypothesis

which action do researchers take to make advances in science

they share their experimental results with other researchers

which statement best describes the variables in a controlled experiment

the independent variable is changed to see its effect on the dependent variable while all other conditions are unchanged

sarah performs an experiment to see whether bees prefer red flowers or yellow flowers. what is the independent variable in this investigation

color of flowers

a student is investigating the question "which increases a person's breathing rate more after three minutes, lifting five-pound weights or lifting ten-pound weights?" she designs an experiment to test the question. which is the dependent variable in her experiment

breathing rate

sarah carried out an experiment to test a hypothesis. some of her data supported the hypothesis, but some refuted it. what is the best thing for sarah to do next

revise her hypothesis, and then retest it

a series of experiments, which are repeated over and over, seem to suggest that a scientific theory is incorrect. what does this most likely mean

the theory must be revised

after observing a moth that is camouflaged against dark-colored bark, a scientist asks a question. the scientist discovers that the question has already been asked and answered by several investigations. what should the scientist do

the scientist should revise the question to address a gap in knowledge

which description indicates that a question is nonscientific

the question relies on moral or social values

scientists recently identified the function of three proteins in plants. the proteins regulate the production of fatty acids, which are found in fats and oils. which question will most likely be asked about the results, leading to more investigation

how can the proteins be used to increase the amount of oil produced by a plant