Which of the following is not the correct name for the formula given? Which is not the correct chemical formula for the compound named? What is the correct formula for barium phosphate? Which formula is not correct? What is the correct formula for chromium VI oxide? Which is the correct formula for gold I sulfide?
A dynamic process is one that is active as opposed to static. In terms of the scientific method, scientists are always performing experiments to prove or disprove a hypothesis or a law or a theory. Scientists do not stop asking questions just because a given theory seems to account satisfactorily for some aspect of natural behavior.
The key to the scientific method is to continually ask questions and perform experiments. Science is an active process, not a static one. The fundamental steps are 1 making observations; 2 formulating hypotheses; 3 performing experiments to test the hypotheses. The key to the scientific method is performing experiments to test hypotheses. If after the test of time the hypotheses seem to account satisfactorily for some aspect of natural behavior, then the set of tested hypotheses turns into a theory model.
However, scientists continue to perform experiments to refine or replace existing theories. A random error has equal probability of being too high or too low. This type of error occurs when estimating the value of the last digit of a measurement. A systematic error is one that always occurs in the same direction, either too high or too low.
For example, this type of error would occur if the balance you were using weighed all objects 0. A random error is an indeterminate error, whereas a systematic error is a determinate error. A qualitative observation expresses what makes something what it is; it does not involve a number; e. The SI units are mass in kilograms, length in meters, and volume in the derived units of m 3. The precision of an instrument is related to the number of significant figures associated with an experimental reading on that instrument.
Different instruments for measuring mass, length, or volume have varying degrees of precision. Some instruments only give a few significant figures for a measurement, whereas others will give more significant figures. Precision: reproducibility; accuracy: the agreement of a measurement with the true value.
Imprecise and inaccurate data: Data can be inaccurate due to a systematic error in the measuring device or with the user. For example, a balance may read all masses as weighing 0. A set of measurements that are imprecise implies that all the numbers are not close to each other. Some say that if the average of imprecise data gives the true value, then the data are accurate; a better description is that the data takers are extremely lucky.
Significant figures are the digits we associate with a number. They contain all of the certain digits and the first uncertain digit the first estimated digit. The result of this is the one-significant-figure answer of 0. From Figure 1. A degree unit on the Fahrenheit scale is not a large as a degree unit on the Celsius or Kelvin scales. For the T F vs. For the T C vs. We should report the total volume to the hundredths place because the volume from the first graduated cylinder is only read to the hundredths read to two decimal places.
The first graduated cylinder is the least precise volume measurement because the uncertainty of this instrument is in the hundredths place, while the uncertainty of the second graduated cylinder is to the thousandths place. It is always the lease precise measurement that limits the precision of a calculation. Volumes are always estimated to one position past the marked volume increments.
The estimated volume of the first beaker is Yes, all volumes could be identical to each other because the more precise volume readings can be rounded to the other volume readings. But because the volumes are in three different measuring devices, each with its own unique uncertainty, we cannot say with certainty that all three beakers contain the same amount of water.
As is always the case, the least precise measurement determines the precision of a calculation. When the result is rounded to the correct number of significant figures, the last significant figure stays the same if the number after this significant figure is less than 5 and increases by one if the number is greater than or equal to 5. The underline shows the last significant figure in the intermediate answers.
Appropriate conversion factors are found in Appendix 6. In general, the number of significant figures we use in the conversion factors will be one more than the number of significant figures from the numbers given in the problem. This is usually sufficient to avoid round-off error.
Temperature Both have the same mass of 1. Classification and Separation of Matter A gas has molecules that are very far apart from each other, whereas a solid or liquid has molecules that are very close together. An element has the same type of atom, whereas a compound contains two or more different elements. Picture i represents an element that exists as two atoms bonded together like H 2 or O 2 or N 2. Pictures iii and iv contain representations of elements that exist as individual atoms like Ar, Ne, or He.
Picture iv represents a gaseous compound. Note that pictures ii and iii also contain a gaseous compound, but they also both have a gaseous element present. Picture vi represents a mixture of two gaseous elements. Picture v represents a solid element. Pictures ii and iii both represent a mixture of a gaseous element and a gaseous compound. Solid: rigid; has a fixed volume and shape; slightly compressible Liquid: definite volume but no specific shape; assumes shape of the container; slightly Compressible Gas: no fixed volume or shape; easily compressiblePure substance: has constant composition; can be composed of either compounds or elements Element: substances that cannot be decomposed into simpler substances by chemical or physical means.
Compound: a substance that can be broken down into simpler substances elements by chemical processes. Homogeneous mixture: a mixture of pure substances that has visibly indistinguishable parts.
Heterogeneous mixture: a mixture of pure substances that has visibly distinguishable parts. Solution: a homogeneous mixture; can be a solid, liquid or gas Chemical change: a given substance becomes a new substance or substances with different properties and different composition. Physical change: changes the form g, l, or s of a substance but does no change the chemical composition of the substance.
Table salt is usually a homogeneous mixture composed mostly of sodium chloride NaCl , but will usually contain other substances that help absorb water vapor an anticaking agent. Initially, a mixture is present. The magnesium and sulfur have only been placed together in the same container at this point, but no reaction has occurred.
When heated, a reaction occurs. Assuming the magnesium and sulfur had been measured out in exactly the correct ratio for complete reaction, the remains after heating would be a pure compound composed of magnesium and sulfur. However, if there were an excess of either magnesium or sulfur, the remains after reaction would be a mixture of the compound produced and the excess reactant. Chalk is a compound because it loses mass when heated and appears to change into another substance with different physical properties the hard chalk turns into a crumbly substance.
Because vaporized water is still the same substance as solid water H 2 O , no chemical reaction has occurred. Sublimation is a physical change. A physical change is a change in the state of a substance solid, liquid, and gas are the three states of matter ; a physical change does not change the chemical composition of the substance. A chemical change is a change in which a given substance is converted into another substance having a different formula composition.
Vaporization refers to a liquid converting to a gas, so this is a physical change. The formula composition of the moth ball does not change. This is a chemical change since hydrofluoric acid HF is reacting with glass SiO 2 to form new compounds that wash away. This is a physical change because all that is happening during the boiling process is the conversion of liquid alcohol to gaseous alcohol. A Only I is true. B Only II is true. C Only III is true.
D All of the statements are true. E Two of the statements are true. Which is the symbol for the isotope of nitrogen that has 7 protons and 8 neutrons?
Which of the following represents a pair of isotopes? The number of protons is the same for all neutral atoms of an element. The number of electrons is the same for all neutral atoms of an element. The number of neutrons is the same for all neutral atoms of an element. Only I and II are true. Only I and III are true. If the mass number of the ion is 24 and it has 10 electrons, what is the element and how many neutrons does it have?
Which element does not belong to the family or classification indicated? Which are alkaline earth halides? Select the group of symbols that would correctly complete the following statements, respectively.
Halogens Noble gases Alkaline earth metals Alkali metals None of these choices. Which of the following formulas is not correct? Which of the following is not the correct chemical formula for the compound named? Which of the following is not the correct name for the formula given?
Which is not the correct chemical formula for the compound named? What is the correct formula for barium phosphate? Which formula is not correct? What is the correct formula for chromium VI oxide?
Which is the correct formula for gold I sulfide? Complete the following table. Write the chemical formulas for the following compounds or ions. Which nuclide has more protons than neutrons? An isotope of an element is formed I. Which statement or statements regarding Antoine Lavoisier and his discovery of the conservation of mass in chemical reactions must be false.
A Lavoisier conducted his experiment in an apparatus that trapped all reaction products. B Lavoisier was able to make accurate mass measurements. C Lavoisier was able to make precise mass measurements. D Lavoisier did not trap gases in his experiments because their mass was negligible. The experiments of what two scientists were instrumental in determining the mass and charge of the electron?
Millions discover their favorite reads on issuu every month.
0コメント