Complete Question
You and your lab partner are asked to determine the density of an aluminum bar. The mass is known accurately (to four significant figures). You use a simple metric ruler to measure its dimensions and obtain the results for Method A. Your partner uses a precision micrometer and obtains the results for Method B.
Method A (g/cm3) 2.2,2.3,2.7,2.4 Method B (g/cm3) 2.703 2.701 2.705 5.811
The accepted density of aluminum is 2.702 g/cm 3 .
(a) Calculate the average density for each method.
Should all the experimental results be included in your calculations? If not, justify any omissions.
(b) Calculate the percent error for each method’s average value.
(c) Calculate the standard deviation for each set of data.
(d) Which method’s average value is more precise? Which method is more accurate?
Answer:
a)[tex]Ma_{avg}= 2.4g/cm^3[/tex]
[tex]Mb_{avg}=2701g/cm^3[/tex]
b)[tex]PE_a=7.5\%[/tex]
[tex]P.E_b=28.8 \%[/tex]
c) [tex]\sigma_A=0.35[/tex]
[tex]\sigma_B=0.0545[/tex]
d)Method A
Explanation:
From the question we are told that:
Method A Density values
2.7
Method B Density values
2.703,2.701,2.705,5.811
Density of aluminium [tex]p_d=2.702 g/cm^3[/tex].
a)
Generally the average density for each method is mathematically given by
Method A
[tex]Ma_{avg}= \frac{2.2+2.3+2.7+2.4}{4}[/tex]
[tex]Ma_{avg}= 2.4g/cm^3[/tex]
Method B
[tex]Mb_{avg}=\frac{2.703+2.701+2.705}{3}[/tex]
[tex]Mb_{avg}=2701g/cm^3[/tex]
b)
Generally the equation for percentage error [tex]PE[/tex] is is mathematically given by
percent error = (measured- real)/real *100
Given real = 2.702 g/ cm3
Method A =
[tex]PE_a=(2.5- 2.702)* \frac{100}{2.702}[/tex]
[tex]PE_a=7.5\%[/tex]
Method B =
[tex]PE_b=( 3.481- 2.702)*\frac{100}{2.702}[/tex]
[tex]P.E_b=28.8 \%[/tex]
c)
Generally the standard deviation [tex]\sigma[/tex] for each method is mathematically given by
Method A
[tex]\sigma=\sqrt{\frac{\sum(x-a)^2}{N} }[/tex]
[tex]\sigma=\sqrt{\frac{0.25+0.16+0+0.09}{4} }[/tex]
[tex]\sigma_A=0.35[/tex]
Method B
[tex]\sigma=\sqrt{\frac{\sum(x-a)^2}{N} }[/tex]
[tex]\sigma=\sqrt{\frac{0.000001+0.00000+0.000009+0.011881}{4} }[/tex]
[tex]\sigma_B=0.0545[/tex]
d)
Therefore with lower percentage error the method who's average value is more precise is
Method A
Which sample contains the greatest number of atoms. A sample of Ca that contains 3.40×1024 atoms or a 1.76 mole sample of Be?
The sample of _____ contains the greatest number of atoms.
Answer:
The sample of __Ca___ contains the greatest number of atoms
Explanation:
As we know,
1 mole [tex]= 6.022*10^{23}[/tex] molecular entities (Can be atom, ions or molecules)
Number of atoms in 1.76 mole sample of Be
[tex]= 6.022*10^{23} *1.76\\= 1.059 * 10^{24}[/tex]
The sample of __Ca___ contains the greatest number of atoms
What are the two types of bonding we have studied?
a. Metallic and covalent
b. Covalent and ionic
c. lonic and metallic
d. Molecular and metallic
Answer:
B: Covalent bond and Ionic bond
The strength of an acid is affected by the polarity of the bond connected to the acidic hydrogen. The more highly polarized this bond, the more easily the hydrogen is ionized. Electronegative atoms or groups of atoms present in the structure of an acid can act to withdraw electrons and produce additional polarization. Two common groups of acids to which this principle can be applied are oxoacids and carboxylic acids. In the latter group, the length of the hydrocarbon chain in a carboxylic acid has very little effect on acid strength Longer chains may slightly diminish acidity. Bases act as hydrogen ion acceptors because of the unshared electron pass in their structure. Any group present in a base that withdraws electrons makes these electron pairs less available to accept a hydrogen ion. In contrast, any group that can act as an electron donating group such as hydrocarbon groups (usually represented as II) can increase the base strength. Thus, the addition of electronegative atoms or groups of atoms to the structure of a base decreases the base strength and electron donating groups increase base strength. Many common weak bases are derivatives of ammonia, in which H atom(s) of NH_2 are replaced with other groups.
Arrange the following oxoacids in order of decreasing acid strength. Rank from strongest to weakest acid.
1. HBrO
2. HClO
3. HClO2
4. HClO3
Answer:
The answer is "[tex]\bold{HClO_3 > HClO_2 >HClO > HBrO}[/tex]"
Explanation:
We arrange oxoacids to decrease the intensity of acids in this question. Or we may conclude all this from strongest to weakest acids they order oxoacids, that's why above given order is correct.
pls help with 1 question (15 ponts)
What happens in the circulatory system?
how much carbon is in CO2 if the sample contains 48 g of oxygen remember the ratio of carbon to oxygen is 12 g of 32 g
18g
24g
12g
20g
Answer: 24g
Explanation:
Suppose that Laser A were to shine a beam of light straight into the left side of Prism A, and Laser B were to shine an identical beam of light straight into the left side of Prism B. Which prism would refract the light more? (Assume the sides of the two prisms are sloped the same.)
Answer:
Prism B
Explanation:
4
In the Hatom , what is the correct order (arrangement) of energy levels
What is the percent of C in
CO2?
(C = 12.01 amu, O = 16.00 amu)
[? ]%
Please help
Answer:0.034%
Explanation:
In 2-3 sentences, explain how objects in our solar system planets acquired the mass to become planets.
The sun contained 99% of the available matter and the rest matter formed smaller clumps inside the spinning disk. These clumps gained enough mass which lead to their gravity shaping them into spheres becoming planets.
What are planets?A planet can be described as a large, rounded astronomical body that is neither a star nor its remnant. The theory of planet formation is the nebular hypothesis, which tells that an interstellar cloud collapses out of a nebula to generate a young protostar orbited by a protoplanetary disk.
The planet grows in this disk by the accumulation of material driven by gravity and this process is known as accretion. Our solar system has at least eight planets that rotate around an axis tilted with respect to its orbital pole.
All planets possess an atmosphere, although that of Mercury is tenuous. The Solar System planets create magnetic fields apart from Venus and Mars, and all planets except Venus and Mercury have natural satellites.
Learn more about planets, here:
https://brainly.com/question/15268075
#SPJ2
write the molecular formula of sodium nitroprusside.
Answer:
Explanation: Sodium Nitroprusside, whose molecular formula is • 2H2O, and whose molecular weight is 297.95. Dry sodium nitroprusside is a reddish-brown powder, soluble in water.
How many grams of carbon disulfide will be produced if .012
kg of sulfur reacts with carbon?
Answer:
14.25g
Explination:
I found this answer on quizlet titled, "Chem Quizlet" by jamie_barbara
3. Calculate the average atomic mass of sulfur if 95.00% of all sulfur atoms have
a mass of 31.972 amu, 0.76% has a mass of 32.971u and 4.22% have a mass of
33.967u.
Answer:
Average atomic mass = 32.057 u
Explanation:
Average atomic mass = Σ(isotope × abundance)
Average atomic mass = (0.95 × 31.972) + (0.0076 × 32.971) + (0.0422 × 33.967)
Average atomic mass = 32.057 u
A dunk tank holds 550,200 grams of water. How many moles of water are in the tank?
Answer:
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Explanation:
Calculate the pH for the following weak acids
.01M Formic acid (HCHO2) aka= 1.7 x 10^-4
Answer:
pH = 2.88
Explanation:
For a weak acid solution, the pH can be calculated using the following formulas:
[H⁺] = [tex]\sqrt{Ka*C}[/tex]pH = -log[H⁺]Where Ka = [tex]10^{-pKa}[/tex] and C is the molar concentration.
We are given Ka and C by the problem, meaning we can now proceed to calculate [H⁺]:
[H⁺] = [tex]\sqrt{1.7*10^{-4}*0.01}[/tex] [H⁺] = 0.0013 MFinally we calculate the pH:
pH = - log (0.0013) = 2.88A] 1 N2 + 3 H2 → 2 NH3
1. How many moles and grams of ammonia can be made from 6.3 moles of H2 ?
2. How many moles and particles of ammonia can be made from 2.5 moles of N2 ?
3. How many moles is 425 g of ammonia? How many moles and grams of N2 are needed to make it?
4. How many moles and grams and liters of H2 are needed to make 10 moles of ammonia?
I haven't done these in some time, so I'm not sure if they are 100% right.
1) 6.3 moles of H2( 2 mol of NH3 / 3 mol of H2)= 4.2 mol of NH3
6.3 moles of H2( 2 mol of NH3/ 3 mol of H2)(17.04 g of NH3/1 mol NH3)= 71.57 g of NH3
2) 2.5 moles of N2(2 mol of NH3/1 mol of N2)= 5 moles of NH3
2.25 moles of N2(2 mol of NH3/ 1 mol of N2)(6.02x10^23 particles/ 1 mol of NH3)= 3.01x10^24 particles of NH3
3) 425 g of NH3(1 mol of NH3/17.04 g NH3)= 24.9 moles of NH3
425 g of NH3(1 mol of NH3/17.04 g of NH3)(1 mol of N2/2 mol of NH3)(28.02 g of N2/1 mol N2)= 349 g of N2
425 g of NH3(1 mol of NH3/17.04 g of NH3)(1 mol of N2/2 mol of NH3)= 12.5 mol of N2
4) 10 moles NH3(3 moles of H2/2 moles of NH3)= 15 moles H2
10 moles NH3(3 mol of H2/2 mol of NH3)(2.02 g of H2/1 mol of H2)= 30.3 g of H2
30.3 g = .0303 liters of H2
During a solar eclipse, explain what would an observer
on the Moon see on the surface of the Earth?
Answer:
It getting darker
Explanation:
This is because the light isn't hitting the earth as much, making it darker. They might also see more city lights than before. Hope this helps! plz mark as brainliest!
help ill mark brainlist !!! (no bots or links)
at a subduction zone, a very low and deep point forms on the surface of the crust. what is this low point called?
A ) Rift
B ) Valley
C ) Ridge
D ) Trench
Answer:
The trench.
Explanation:
A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex.
Someone please help me
Answer:
D - synapse
Explanation:
Synapse, also called neuronal junction, the site of transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector). A synaptic connection between a neuron and a muscle cell is called a neuromuscular junction.
Which halogens are gases at STP?
As the atomic number increases, the reactivity of the halogens decreases. Fluorine and chlorine exist as gases at room temperature, while bromine is a liquid, and iodine is a solid.
Answer:
As the atomic number increases, the reactivity of the halogens decreases. Fluorine and chlorine exist as gases at room temperature, while bromine is a liquid, and iodine is a solid.
Pls help with the question.
Answer:
2 L
Explanation:
From the question
Applying boyles law,
PV = P'V'....................... Equation 1
Where P = Initial pressure, P' = Final Pressure, V = Initial Volume, V' = Final Volume.
make V' the subject of the equation
V' = PV/P'.................... Equation 2
Givne: V = 5 L, P = 500 mmHg, P' = 1240 mmHg
Substitute these values into equation 2
V' = (5×500)/1240
V' = 2500/1240
V' = 2 L
SSA PRACTICE QUESTION
Mandy wanted to see if a new
environmentally-friendly pesticide will
prevent insect damage to tomato plants.
After making a hypothesis, she conducts
her experiment. She treats five tomato
plants with traditional pesticide and five
with the new pesticide. Mandy also
leaves five plants untreated as a control.
She makes careful notes of how she set
up her experiment and then records her
data about all of the plants. Why is it
important for Mandy to record her
procedures and data accurately?
Answer:
The correct answer is - so that other scientists can replicate the experiment and make sure the results are correct or to check accuracy.
Explanation:
The data and procudres are required to be recorded or noted correctly so the experiment and research can be replicate and tested for the accuracy of the experiment by other scientist and researcher.
Mandy also need to note procedure, data, variables and other data correctly for the testing the accuracy and replication of the experiment. The replication is essential to check if every thing is correct and result are error free.
Write a word equation and a skeleton equation for the chemical reaction.
A. Solid iron reacts with aqueous copper(ii) nitrate to produce solid copper and aqueous iron(ii) nitrate.
A lab requires 3.50L of a 2.0M solution of HCl. What volume of a 6.0M solution is needed to make this solution?
Answer:
THE ANSWER IS 1.167L
Explanation:
What is the relative atomic mass of an element
whose isotopic composition is 90% of 20x and 10% of 22x
Answer:
20.2 amu.
Explanation:
Let A represent isotope ²⁰X
Let B represent isotope ²²X
From the question given above, the following data were obtained:
For Isotope A (²⁰X):
Mass of A = 20
Abundance (A%) = 90%
For Isotope B (²²X):
Mass of B = 22
Abundance (A%) = 10%
Relative atomic mass (RAM) =?
The relative atomic mass (RAM) of the element can be obtained as follow:
RAM = [(Mass of A × A%)/100] + [(Mass of B × B%)/100]
RAM = [(20 × 90)/100] + [(22 × 10)/100]
RAM = 18 + 2.2
RAM = 20.2 amu
Thus, relative atomic mass (RAM) of the element is 20.2 amu
what statement is the best description of a chemical bond
Answer:
A chemical bond holds atoms together.
Select all of the answers that apply.
Which of the following characteristics must an air mass have?
It flows as one unit.
It has different temperatures but uniform humidity.
It must be 1,000 miles or more in size.
It must form over a low-pressure area.
It has a uniform temperature and humidity.
Explanation:
it has different temperature but uniform humidity
hope it will help you
How many moles of water are produced from burning 80 moles of
methane in excess oxygen?
Answer:
160 mol H₂O
Explanation:
Step 1: Write the balanced complete combustion reaction
CH₄ + 2 O₂ ⇒ CO₂ + 2 H₂O
Step 2: Establish the appropriate molar ratio
According to the balanced equation, the molar ratio of CH₄ to H₂O is 1:2.
Step 3: Calculate the moles of water formed from 80 moles of methane
We will use the previously established molar ratio.
80 mol CH₄ × 2 mol H₂O/1 mol CH₄ = 160 mol H₂O
Help me pls I put 49 point( every single point that I have) pls help me
Answer:
see below
Explanation:
1) chem rxn compound molecule covalent ions ionic
2) 2 hydrogen one oxygen H2O covalent
3) is always liq
What is created when an acid is mixed with a base?
Answer:
If you mix equal amounts of a strong acid and a strong base, the two chemicals essentially cancel each other out and produce a salt and water. Mixing equal amounts of a strong acid with a strong base also produces a neutral pH (pH = 7) solution.
Use average bond enthalpies (linked above) to calculate the enthalpy change for the following gas-phase reaction. CO(g) + Cl2(g) COCl2(g) To analyze the reaction, first draw Lew To analyze the reaction, first draw Lewis structures for all reactant and product molecules. ΔHreaction = ------ kJ Draw the reaction using separate sketchers for each species. Separate multiple reactants and/or products using the + sign from the drop-down arrow. Separate reactants from products using the → symbol from the drop-down menu. Remember to include nonbonding valence electrons in your Lewis structures. To analyze the reaction, first draw Lewis structures for all reactant and product molecules. Draw the reaction using separate sketchers for each species. Separate multiple reactants and/or products using the + sign from the drop-down arrow. Separate reactants from products using the → symbol from the drop-down menu. Remember to include nonbonding valence electrons in your Lewis structures. To analyze the reaction, first draw Lewis structures for all reactant and product molecules. Draw the reaction using separate sketchers for each species. Separate multiple reactants and/or products using the + sign from the drop-down arrow. Separate reactants from products using the → symbol from the drop-down menu. Remember to include nonbonding valence electrons in your Lewis structures.
Answer:
ΔHreaction (KJ) = - 78 KJ
The value may vary in relation to the source of the bond enthalpy data.
Bond enthalpies used (From a table of bond enthalpies )
Bond KJ/ mol
C≡O 1080
C-Cl 330
C=O 741
Cl-Cl 243
Explanation:
CO(g) + Cl2(g) → COCl2(g)
1) Lewis structures
Valence electrons
C 4
O 6
Cl 7
Reactants
CO(g)
In the case of CO, carbon has a negative charge and oxygen a positive charge.
Cl2(g)
Products
COCl2(g)
_______________________
ΔHreaction (KJ) = ∑ n* ΔH ( reactants) - ∑ n* ΔH (product)
ΔHreaction (KJ) = (ΔHC≡O + ΔHCl-Cl) - ( ΔHC=O + 2* ΔHC-Cl)
Replacing the values
ΔHreaction (KJ) = (1080 + 243) - ( 741 + 2* 330)
ΔHreaction (KJ) = 1323 - 1401
= - 78 KJ