Four different methods are described for validating the results of a particular analysis. Indicate for each whether the method primarily checks the accuracy of the analysis or the precision of the analysis. Method 1: Five aliquots of the same sample are injected for a gas-chromatographic analysis by one person on the same day. a. precision.b. accuracy.Method 2: A known amount of analyte is added to an aliquot of the sample and analyzed with the sample. a. precision.b. accuracy. Method 3: Aliquots from a blood sample are sent to three separate laboratories for analysis using the same method. a. precision.b. accuracy. Method 4: Identical standards are analyzed by two different methods. a. accuracy.b. precision.
Answer:
Method 1 - precision
Method 2 - accuracy
Method 3 - precision
Method 4 - accuracy
Explanation:
The accuracy of a method refers to how close the experimental result is to the accepted value. Accuracy could be checked by carrying out the required test on the standard and not on the sample or by adding a known amount of analyte to the sample so that the results obtained can be carefully compared.
Precision on the other hand, refers to how close the results of a replicate analysis are to each other. In testing for precision, the analysis must be carried out several times, in order to check how close the results are to each other.
Do all variations help organisms survive
Answer:
Yes
Explanation:
Or maybe i dont really know what it mean
We should exhaust all possiblr resources from nature says a miner?
Answer: No
Explanation: Some scientists have declared that mineral deposits containing important non renewable resources such as copper and zinc will be exhausted in a few decades if consumption does not decrease.
what is extraction .....???
Answer:
Extraction is the action of removing something.
Explanation:
A 4.534 g sample of a solid mixture was analyzed for barium ion. First the rock was crushed in a mortar and pestle. 100% of the sample was transferred to a beaker, where it was dissolved in 150.0 mL of d.i. water. to give 152 mL of solution. The aqueous sample was then analyzed by adding a small excess of sulfuric acid. The resultant reaction produced a precipitate of barium sulfate, which was collected by filtration, rinsed, dried and weighed. If 0.5376 g of barium sulfate was obtained, what was the mass percent of barium in the original sample? What was the molar concentration barium in the 152 mL of solution prior to adding sulfuric acid? Show work clearly; include a balanced net ionic chemical equation, units and sig. figs.
Answer:
6.976%
0.0152 M
Explanation:
Step 1: Write the balanced chemical equation
Ba²⁺(aq) + H₂SO₄(aq) ⇒ BaSO₄(s) + 2 H⁺(aq)
The balanced net ionic chemical equation is:
Ba²⁺(aq) + SO₄²⁻(aq) ⇒ BaSO₄(s)
Step 2: Calculate the moles corresponding to 0.5376 g of BaSO₄
The molar mass of BaSO₄ is 233.39 g/mol.
0.5376 g × (1 mol/233.39 g) = 2.303 × 10⁻³ mol
Step 3: Calculate the moles of Ba²⁺ that produced 2.303 × 10⁻³ moles of BaSO₄
The molar ratio of Ba²⁺ to BaSO₄ is 1:1. The moles of Ba²⁺ are 1/1 × 2.303 × 10⁻³ mol = 2.303 × 10⁻³ mol.
Step 4: Calculate the mass corresponding to 2.303 × 10⁻³ moles of Ba²⁺
The molar mass of Ba²⁺ is 137.33 g/mol.
2.303 × 10⁻³ mol × 137.33 g/mol = 0.3163 g
Step 5: Calculate the mass percent of barium in the original sample
0.3163 g of barium ion were in a 4.534 g-sample. The mass percent of barium ion is:
0.3163 g/4.534 g × 100% = 6.976%
Step 6: Calculate the molar concentration barium in the 152 mL of solution
2.303 × 10⁻³ moles of barium ion were in 152 mL (0.152 L) of solution. The molarity of barium ion is:
M = 2.303 × 10⁻³ mol/0.152 L = 0.0152 M
Why is digestion an example of both physical and chemical change simultaneously
Answer: Here is why,
Explanation: Burning of wood is a example of both physical and chemical change. ... Another example is digestion of food ,first the food is chewed into small pieces this is a chemical change while in the actual digestion process it is chemically broken with the help of digestive enzymes and saliva
You have 100. grams of potassium bromide (KBr). How many moles do you have? (1 mole KBr = 119 g KBr)
0.840 mole KBr
1.00 mole KBr
1.19 mole KBr
2.00 mole KBr
Answer:
0.840
Explanation:
The 100 grams of KBr have been equivalent to 0.84 moles. Thus, option A is correct.
The moles can be defined as the mass of the compound with respect to the molecular mass. The moles can be given as:
Moles = [tex]\rm \dfrac{weight}{Molecular\;weight}[/tex]
The molecular weight has been the mass of the constituents of the atoms present in the compound.
The compound KBr has a molecular mass of 119 g/mol.
The given mass of the compound has been 100 grams.
The moles of KBr can be given as:
Moles of KBr = [tex]\rm \dfrac{100}{119}[/tex]
Moles of KBr = 0.84 moles.
The 100 grams of KBr have been equivalent to 0.84 moles. Thus, option A is correct.
For more information about the moles, refer to the link:
https://brainly.com/question/2437143
Using Beer's Law determine the concentration of a dye dissolved in water that has an absorptivity of 1 x 102 cm-1M-1 and produces an absorbance reading 1.0. The length of the cuvette is 1 cm.
Answer:
1 × 10⁻² M
Explanation:
Step 1: Given data
Absorptivity of a dye (ε): 1 × 10² cm⁻¹M⁻¹
Absorbance (A): 1.0
Length of the cuvette (l): 1 cm
Concentration of a dye (C): ?
Step 2: Calculate the concentration of the dye
We will use Beer's Law.
A = ε × l × C
C = A / ε × l
C = 1.0 / 1 × 10² cm⁻¹M⁻¹ × 1 cm
C = 1 × 10⁻² M
The concentration of the dye is 1 × 10⁻² M.
Consider the reaction and indicate which reactant is the Lewis acid and which is the Lewis base. C H 3 C O Cl and F e C L 3 give F e C L 4 minus and C H 3 C O plus. The structure of C H 3 C O C L is a central carbon double bonded to an oxygen containing two lone pairs. The central carbon is also bonded to a methyl group and a chlorine, which contains three lone pairs. The product is a central carbon with a plus charge, which is double bonded to an oxygen which contains two lone pairs. THe carbocation is also bonded to a methyl group. Identify the true statement(s).
Answer:
[tex]\mathbf{FeCl_3}[/tex] is the lewis acid
[tex]\mathbf{CH_3COCl}[/tex] is the lewis base
Explanation:
The Lewis acid is a compound capable of accepting a doublet of electrons and which has an electronic gap on its valence layer.
The lewis base is a compound capable of donating a doublet of electrons.
A Lewis acid associates with a Lewis base through a covalent bond (sharing of two electrons between two atoms). The reaction between an acid and a Lewis base produces a compound called the Lewis adduct.
We can see the illustration of the diagrammatic expression in the image attached below.
How many total atoms are in one molecule of maltose?
Answer:
The total number of atoms is 12 + 22 + 11 = 45, so carbon atoms are 12/45 of the total.
Explanation:
What will happen when the valve between a 2.00-L bulb, in which the gas pressure is 2.00 atm, and a 3.00-L bulb, in which the gas pressure is 4.50 atm, is opened? Assume the temperature remains constant. (For this question, label each statement as True or False and give an explanation/justification for each of your answers to receive credit. No credit is given for only True or False answers with no adequate justification. To receive credit you must provide justification. You may have to give numerical answers followed by verbal explanations. You can use any reasoning that you see fit but be as thorough as possible.)
The two gases will mix and react.
The two gases will remain separate and will not mix.
The two gases will occupy a volume of 5.0 L and the final pressure in the two bulbs will be 6.50 atm.
The two gases will occupy a volume of 5.0 L and the final pressure in the two bulbs will be 3.50 atm.
The two gases will occupy a volume of 5.0 L and the final pressure in the two bulbs will be 3.25 atm.
Answer:
- The two gases will mix and react.: FALSE.
- The two gases will remain separate and will not mix: FALSE.
- The two gases will occupy a volume of 5.0 L and the final pressure in the -two bulbs will be 6.50 atm.: FALSE.
- The two gases will occupy a volume of 5.0 L and the final pressure in the two bulbs will be 3.50 atm.: TRUE.
- The two gases will occupy a volume of 5.0 L and the final pressure in the two bulbs will be 3.25 atm: FALSE.
Explanation:
Hello.
In this case, given the options, since the total volume of the container includes the both of them, we find that:
- The two gases will mix and react: FALSE, since we do not know the identity of the gases which could be the same or two different inert gases.
- The two gases will remain separate and will not mix: FALSE, since as the valve is opened, the total gas will occupy the entire volume as the volume of a gas is the same to the container based on its constant molecules movements.
- The two gases will occupy a volume of 5.0 L and the final pressure in the two bulbs will be 6.50 atm: FALSE, since in this case, by using the Boyle's law for the first compartment we obtain the pressure of the gas there:
[tex]P_2V_2=P_1V_1\\\\P_2=\frac{P_1V_1}{V_2} =\frac{2.00atm*2.00L}{5.00L} =0.8atm[/tex]
Now, we reuse it for the gas at the 3.00-L bulb to find its final pressure:
[tex]P_2V_2=P_1V_1\\\\P_2=\frac{P_1V_1}{V_2} =\frac{2.00atm*3.00L}{5.00L} =2.7atm[/tex]
So the final pressure is:
[tex]P_{TOTAL}=0.8atm+2.7atm\\\\P_{TOTAL}=3.5atm[/tex]
- The two gases will occupy a volume of 5.0 L and the final pressure in the two bulbs will be 3.50 atm: TRUE considering the total pressure computed above.
- The two gases will occupy a volume of 5.0 L and the final pressure in the two bulbs will be 3.25 atm: FALSE since the final pressure is 3.5 atm.
Regards.
3) A certain reaction has the following general form: A + B à AB At a particular temperature the concentration versus time were collected for this reaction, and a plot of ln[A]t versus time resulted in a straight line with a slope of −3.7 x 10−3 s−1. Show your math! (5 points) a. What is the order of the reaction? b. What is the rate constant (including units)? c. Calculate the half-life for the reaction. d. If the initial concentration of A is 0.250 M, what is the concentration after 220 seconds?
Answer:
a. First order.
b. [tex]k=3.7x10^{-3}s ^{-1}[/tex]
c. [tex]t_{1/2}=187.3s[/tex]
d. [tex][A]=0.111M[/tex]
Explanation:
Hello.
a. In this case since the slope is in s⁻¹ we can infer that the lineal form of the rate law is:
[tex]ln[A]=-kt+ln[A]_0[/tex]
Which is also:
[tex]y=mx+b[/tex]
It means that the reaction is first-order as slope equals the negative of the rate constant which also has units of first-oder reaction.
b. Since the slope is −3.7 x 10−3 s−1 the rate constant is:
[tex]k=-m\\\\k=-(-3.7x10^{-3}s ^{-1})\\\\k=3.7x10^{-3}s ^{-1}[/tex]
c. For first-order reactions, the half-life is:
[tex]t_{1/2}=\frac{ln(2)}{k}\\ \\t_{1/2}=\frac{ln(2)}{3.7x10^{-3}s^{-1}}\\\\t_{1/2}=187.3s[/tex]
d. In this case, since the integrated first-order rate law is:
[tex][A]=[A]_0exp(-kt)[/tex]
The concentration once 220 seconds have passed is:
[tex][A]=0.250Mexp(-3.7x10^{-3}s^{-1}*220s)\\\\[/tex]
[tex][A]=0.111M[/tex]
Regards.
In a hot shower or steam room, you look up at the ceiling. What do you observe on the ceiling and why?
HELP NOW PLEASE
A substance is matter that is ____ and has a ____ composition?
hydrogen peroxide slowly decomposes into water and oxygen.the enthalpy change of reaction can be calculated using standard enthalpies of formation.Using a Hess cycle what is the enthalpy change of reaction for this decomposition
It is one of the factors affecting metamorphic rock which creates lineation.
Answer:
Pressures and temperatures
Explanation:
In deciding the new substances that develop in a metamorphic stone, pressures and temperatures are major factors. Under various conditions of pressure and temperature, various minerals form.
Metamorphic rocks are classified that, extreme heat and strain, have altered shape. Metamorphic derives from the terms meta and morph in german. Meta means alteration and morph means shape. So, to alter shape, we get metamorphosed significance.
Determine the milliliters of paint in a 5.0 gallon bucket
Ans: 18950 ML
Answer:
the answer is 18,927,06.
Explanation:
I just took the test ; )
Rosa uses a microscope to look at a group of cells. She sees that the cells are joined together, so she knows that they are from one organism. She also sees that all of them have cell walls. Rosa could be looking at which type of cells?
Answer:
Mushroom cells
Explanation:
They are mushroom cells because they are together.
HELP HELP PLEASE ILL GIVE BRAINLEST
compare the circulatory system of a frog and the circulatory system found in humans
Answer:
Frogs have three circuits for their circulation, unlike humans who only have two. Like humans, however, frogs have a systemic circuit, which pumps oxygenated blood throughout the body. The pulmonary circuit moves blood to the lungs to pick up oxygen.
Explanation:
Answer:
A
Explanation:
You are asked to devise a procedure for quality control in a fertilizer plant to check that the nitrogen and phosphorus content is within a specified range. You decide on the outlined steps to monitor a production run of 1000 bags of fertilizer. A. A 50 g sample is removed from every 100th bag of fertilizer produced, resulting in ten 50 g samples. B. Samples 1, 3, 5, 7, and 9 are thoroughly mixed and a 50 g sample of the mixture is removed. C. Samples 2, 4, 6, 8 and 10 and the 50 g sample from the mixture are taken to the analytical laboratory. D. Each 50 g sample is separately dissolved in a fixed volume of water and the solution is filtered to determine the quantity of insoluble material. E. Separate aliquots of the water solutions are subjected to the procedures of phosphorus and nitrogen analysis.
Answer:
Options : A, B and C are correct procedure for quality control in a fertilizer plant
Explanation:
The options that constitute the sampling plan are :
A) A 50 g sample is removed from every 100th bag of fertilizer produced, resulting in ten 50 g samples
B) Samples 1, 3, 5, 7, and 9 are thoroughly mixed and a 50 g sample of the mixture is removed
C) Samples2,4,6,8 and 10 and the 50 g sample from the mixture are taken to the analytical laboratory.
A quality control procedure is used to ensure that a certain product is produced following set standards or meets the required quality desired by the customer . and options A, B and C ensures that.
A beaker contains 42.0 mL of carbon tetrachloride ( CCl4 , density is 1.59 g/mL). Determine how many molecules of carbon tetrachloride are in the beaker.
Answer:
Number of molecules = 2.61 x 10²³
Explanation:
Given:
Volume of tetra-chloride = 42 ml
Density = 1.59 g/ml
Find:
Number of molecules
Computation:
Mass = Volume of tetra-chloride x Density
Mass = 42 x 1.59
Mass = 66.78
Molecular mass of tetra-chloride = 154 g/mol
Moles = 66.78 / 154
Moles = 0.4337
0.4337 mole = 0.4337 x Avogadro number
0.4337 mole = 0.4337 x 6.022 x 10²³
Number of molecules = 2.61 x 10²³
How many grams of mgcl2 must be provided 1.89 mole of chloride ions
Answer:
Mass = 89.97 g
Explanation:
Given data:
Number of moles of chloride ions = 1.98 mol
Mass in grams of MgCl₂ present = ?
Solution:
we can see that 1 mole of MgCl₂ contain 2 moles of chloride ions. Thus 1.89 moles of chloride ions contain moles of MgCl₂ are,
Cl₂ : MgCl₂
2 : 1
1.89 : 1/2×1.89 = 0.945
Thus, 1.89 moles of chloride ions are provided by 0.945 moles of MgCl₂.
Mass of MgCl₂:
Mass = number of moles × molar mass
Mass = 0.945 mol × 95.211 g/mol
Mass = 89.97 g
Some dog foods contains corn and wheat that provide the dog with carbohydrates. Which claim explains why carbohydrates are important to cell processes?
A) They are a source of energy.
B) They make amino acids.
C) They form cell membranes.
D) They help chemical processes happen.
(Science 7th grade)
Hello!
The answer is that they are a source of energy!
Hope this helps!
How many days are in 5.75 weeks?
Answer:
There are 40.25 days in 5.75 weeks
Answer: 40.25
Hope this helped! :)
What do you notice about the relationship between the force strength and the size of the velocity change?
Answer:
fkv SFHHHHHHHHHCB FSSSSZCHJjjjb .SFFHHHHHHHHC
Explanation:
What do you notice about the relationship between the force strength and the size of the velocity change?
Uuuuuuu
(b) in the direct hydration method, ethene reacts with steam. The equation for this reaction is C2H4 + H2O = C2H5OH
State the temperature and pressure used in this reaction.
Answer:
20 degree and 4000000N
When naming CoOH, which Roman numeral should be used?Immersive Reader
(A) I
(B) II
(C) III
(D) IV
PLZ HELP I'LL MARK BRAINLIEST
Answer:
coochie man? lol it's probably D or B :D
In the warm up, you reviewed the equation to calculate
kinetic energy. What question could you ask about kinetic
energy which will include the variables that affect it?
Answer:
Can be used to do work,and it can be converted to potential.
Explanation:
Answer: can it be used to do work
Explanation:
Which example describes a use for gemstones?
fabrics
plastics
drill bits
paper clips
I will give Brainlyest
Answer:
drill bits
Explanation:
I don't think that you would use gemstones in anything else.
Can someone suggest some really good scientific topic for my scientific presentation?