Conversion factor equivalence statement

It is often necessary to convert one metric unit to another. Suppose you needed to convert 4.5 cm into the equivalent length in millimeters. A conversion factor is used to do this. Conversion factor statements always have the form ... 

Remember that two conversion factors can be derived from each equivalence statement. In this case, the equivalence statement 2.54 cm = 1 in. gives... 

Changing from one unit to another via conversion factors (based on the equivalence statements between the units) is often called dimensional analysis. We will use this method throughout our study of chemistry. 

Step 1 To convert from one unit to another, use the equivalence statement that relates the two units. The conversion factor needed is a ratio of the two parts of the equivalence statement. 

Why must a conversion factor come from an equivalence statement ... 

Step 1 To convert from centimeters to inches, we need the equivalence statement 1 in. = 2.54 cm. This leads to two conversion factors ... 

What is an equivalence statement How many conversion factors can be created from one equivalence statement Choose an equivalence statement from Table 5.7, and write all the possible conversion factors from it. 

Conversion factors are huilt from an equivalence statement which shows the relationship between the units in different systems. 

The appropriate equivalence statement is 1 Na atom = 22.99 amu which gives the conversion factor we need ... 

We now want to use this equivalence statement to obtain the conversion factor (mole ratio) that we need. Because we want to go from moles of H2O to moles of O2, we need the mole ratio... 

Next we change the volume of the solution from milliliters to liters, using the equivalence statement 1 L = 1000 mL, which gives the appropriate conversion factor. 

This chemistry course may have been the first time you have encoimtered the method of dimensional analysis in problem solving. Explain what are meant by a conversion factor and an equivalence statement. Give an everyday example of how you might use dimensional analysis to solve a simple problem. 

The present average body burden of strontium-90 in the world s population is about 0.0002 uc. per person. This corresponds, with Dr. Finkel s conversion factor (5 to 10 /tc. per 70-kg man equivalent to 1 /xc. retained per kg for mice) to a retained dose a = 0.00002 to 0.00004 /xc/kg in mice. Hence in order to justify Dr. Finkel s statement evidence would be needed that the mouse threshold is as great as about 0.00004 /xc/kg that is, we must place a in equation (28) equal to 0.00004 gc/kg. From the values of the constant v in Table 2 (we use the values for v = 170 days, which we believe to be better than those for a = 284 days) we find M = 1 X 10 for the minimal test and 3.4 X 10 for the most powerful test with 10 per cent type-II error, and 3.3 X 10 and 13.5 X 10, respectively, with 1 per cent type-II... 

AH is given in kJ per mole. In the balanced equation, the coefficient of CgHig is 2. The equation represents 2 mol CgHig. The energy conversion factor is either 10,942 kJ/2 mol CgHig from the equation or 5471 kJ/mol CgH g from the statement of the problem. The two energy conversion factors are equivalent. Our setup will use the one with the coefficients from the equation. 

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