Calculated according to the rules of significant digit arithmetic 0 0325 5 103 60 06 139 8 Urgent ex

Note: The so-called significant figures: Specifically, they refer to the numbers that can actually be measured in the analysis work.

What can be measured is an uncertain number that includes the last bit of the estimate. We call accurate numbers obtained by direct reading reliable numbers; The part of the number that can be estimated is called a doubtful number. All digits with one suspicious digit that reflect the size of the measurement result are called significant figures.

Efficacy figures. (1) (2) (3) (4) (1) (2) (3) (4) 2 The following equation is calculated according to the rules of significant number operation. (1) (2) (3)ph=, find h+ 1) (2) (3) h+ = 3 Determine the content of Cl in a sample, and obtain the following results

40% to calculate the average value of the determination.

Mean deviation, relative mean deviation, standard deviation, and relative standard deviation.

r = s = rsd= 4 A and B used the same method to determine the content of a component in the same sample, and the analysis results are as follows: A40%；B

41% asked: (1) whether there are outliers; (2) which set of data has good precision; and (3) whether there was a significant difference in the precision of the analysis results between the two people.

1) No outliers (2) S A = S B = A has good precision (3) There is no significant difference in the precision of the analysis results of the two people 5 A standard sample contains sulfur, and the analyst uses a new method to determine the sulfur content in a sample, and the result of four measurements is1190%。Judgment in confidence.

At 95%, is there a systematic error in the new method? Therefore, it is considered that there is a significant difference in the t-meter of the t-meter, and there is a systematic error in the new method 6The percentage content of cuo in the sample was measured 5 times, and the results (%) were

04 And, try the Q test method to determine whether the suspicious value is discarded? (A confidence level of 90% is required, q is = , and suspicious values should be retained because q is required.) 7. Use potassium hydrogen phthalate as the reference material to calibrate the NaOH solution, accurately weigh the potassium hydrogen phthalate on the analytical balance, titrate it with the NaOH solution, and find the concentration of the substance in the NaOH solution.

CNOH = mol·l-1 8 known titer of a hydrochloric acid standard solution THC= g ml. Trial calculation: (1) Titer equivalent to NAOH.

2) Titer equivalent to CAO. (1) Titer equivalent to NaOH: g ml (2) Titer equivalent to CAO:

g ml 9 To make the titration consume mol·l-1HCl solution 20 25 ml, ask should be weighed for analytical purity.

How many grams of reagent Na2CO3 are there? The analytically pure reagent Na2CO3 should be weighed: 10 The NaCl sample should be weighed, dissolved in water, and diluted to scale in a 250 ml measuring flask.

The test solution was pipetted and titrated to the endpoint with mol·L-1AGno3 solution, and the percentage of NaCl content in the sample was calculated. nacl%=

The last significant figure is an estimate, and only one estimate can be retained, and it makes no sense to keep more, because the high and large numbers are unreliable, not to mention the low decimal places in the back. For example, the last digit of centimeters is centimeters, which is estimated to be high in acres.

Therefore, the rules of significant number operation: all of them can be calculated first, and then one more estimate can be retained; Or for each number, just keep it at the highest estimate first. For example, this question should be kept to two decimal places.

The middle digit is an unreliable number from the beginning, because the middle digit is an unreliable number, a reliable number + an unreliable number is an unreliable number, and only one unreliable number can be retained in the significant digit).

Calculate how much is equal according to the rules of significant number crunching.

Summary. Calculated according to the rules of significant number operation, significant figures are a few decimal places.

Calculated by 2 significant digits.

Calculated by 1 significant digit.

Calculated according to the rules of operation of significant figures: equals.

Calculations are made according to the rules of operation of significant figures:

2.Calculated according to the rules of significant digit operation, (

Hello dear, glad to answer for you, 2Calculated according to the rules of significant digit operation, (A significant number crunching rule is a specification that controls the precision of double-precision floating-point number operations.

It points out the accuracy check of the operand before the operation and the writing requirements of how many decimal places are retained in the operation result, so as to reduce the size of the error and its cause. To calculate the equation mentioned above, the precision of the operand will first be adjusted to the significant digit (the significant number operation rule stipulates that for the operation results that meet the requirements of the significant number operation rule, the calculation result can be calculated with standard precision, and the significant precision can be used next to the paragraph, but the final result will retain the maximum allowable significant bits. ), i.e., before calculation, and will retain 2 decimal places.

Summary. Because it is accurate to two decimal places, it is based on two decimal places.

According to the operation rules of significant figures, try to calculate: and explain the operation rules.

Ahh Because it is accurate to two decimal places, it is based on two decimal places.

Other data are accurate to the third decimal place.

Accurate to the third decimal place.

It is already in the third decimal place, and it is not necessary to be exact.

Add them three more numbers.

That is, it is accurate to two decimal places.

Accurate to two decimal places.

Add up the three numbers again:

That's the final answer.

Here is an introduction to the operation rules of significant digit addition and subtraction, first according to the data with the least number of digits after the decimal point, the number of digits of other numbers is retained, and then the addition and subtraction are calculated.