HELP
1. A student determines that the number of grams in a sample of Al2O3 is 18.3 grams. How many moles are in the sample?
2. A chemist needs 35 grams of CaO for a chemical reaction. How many moles of CaO are needed for the chemical reaction?
3. For an acid-base titration, 126 grams of H2SO4 were needed. How many moles of H2SO4 were needed for the Laboratory Activity?
4. A student needs 100 g of vinegar (CH3COOH) for a lab activity. How many moles does the student need?
Answer:
Explanation:
1)
Given data:
Mass of Al₂O₃ = 18.3 g
Number of moles = ?
Solution:
Number of moles = mass/molar mass
Number of moles = 18.3 g/ 101.96 g/mol
Number of moles =0.18 mol
2)
Given data:
Mass of CaO needed = 35 g
Number of moles = ?
Solution:
Number of moles = mass/molar mass
Number of moles = 35 g/ 56 g/mol
Number of moles =0.625 mol
3)
Given data:
Mass of H₂SO₄ needed = 126 g
Number of moles = ?
Solution:
Number of moles = mass/molar mass
Number of moles = 126 g/ 98.1 g/mol
Number of moles = 1.28 mol
4)
Given data:
Mass of vinegar = 100 g
Number of moles = ?
Solution:
Number of moles = mass/molar mass
Number of moles = 100 g/ 60.1 g/mol
Number of moles = 1.66 mol
When metals, non metals,and metallics are composed according to luster, which is best description of the appearance of metalloids
Answer:
Metalloids are metallic-looking brittle solids that are either semiconductors or exist in semiconducting forms, and have amphoteric or weakly acidic oxides. Typical nonmetals have a dull, coloured or colourless appearance; are brittle when solid; are poor conductors of heat and electricity; and have acidic oxides.
Explanation:
Metalloids are sometimes known as semimetals. Metalloids are yellow elements on the periodic table that often lie along the stair-step line.
What are Semimetals ?Metals are at the bottom left of the periodic table, and non-metals are at the top right.
Semimetals are found at the diagonal dividing line between metals and non-metals.
If there is barely any overlap between the top and bottom of the valence band, a substance is classified as a semimetal.
According to the electronic band theory, solids can be classified as metals, semimetals, insulators, or semiconductors.
An element that resembles metal in some ways but is not a metal For instance, although arsenic is a metalloid and appears to be a metal, it really conducts electricity poorly.
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Provide an example of a Food Chain.
Answer: Diamond is the name ^-^
A food chain only follows just one path as animals find food. eg: A hawk eats a snake, which has eaten a frog, which has eaten a grasshopper, which has eaten grass. A food web shows the many different paths plants and animals are connected. eg: A hawk might also eat a mouse, a squirrel, a frog or some other animal.
Hope this helps ^_^
The chemical reaction between iron (Fe) and oxygen (O) results in the loss of electrons from iron. This reaction is an example of _____.
A) respiration
B) sublimation
C) oxidation
D) combustion
Answer:
d combustion because iron and oxegen need eachother
Answer:
The Correct answer would be Oxidation.
Explanation:
if there is no mass # and n # how do you find the mass # and n #
2.If a liquid has a volume of 5800 mL and you need the volume in Liters, will the number appear to
become smaller or larger?
Answer:
The number becomes smaller
Explanation:
Volume = 5800mL
To be converted to L
The relationship between mL and Liters is given as;
1 L = 1000 mL
This means that;
1 L = 1000 mL
x L = 5800 mL
x = 5800 / 1000 = 5.8 L
Comparing 5.8 with 5800, the number becomes smaller.
Now consider a sample of the gas at 33 deg C, 744 mm Hg, and 450 mL. If the pressure is decreased to 725 mm Hg and the temperature raised to 66C. What is the new volume of the gas? New volume =
Answer:
V₂ = 511.59mL
Explanation:
Given data:
Initial volume = 450 mL
Initial pressure = 744 mmHg
Initial temperature = 33°C (33 +273 = 306 K)
Final temperature = 66°C (66+273 = 339 K)
Final pressure = 725 mmHg
Final volume =?
Formula:
P₁V₁/T₁ = P₂V₂/T₂
P₁ = Initial pressure
V₁ = Initial volume
T₁ = Initial temperature
P₂ = Final pressure
V₂ = Final volume
T₂ = Final temperature
Solution:
V₂ = P₁V₁ T₂/ T₁ P₂
V₂ = 744 mmHg × 450 mL × 339 K / 306 K ×725 mmHg
V₂ = 113497200 mmHg .mL. K / 221850 K.mmHg
V₂ = 511.59mL
A Rolaids tablet contains calcium for neutralizing stomach acid. if a Rolaids tablet neutralizes 24.65ml of 0.547m hydrochloric acid, how many milligrams of calcium carbonate are in a Rolaids tablet?
There are 674 mg of calcium carbonate in a Rolaids tablet
Further explanationReaction
CaCO₃ + 2HCl ⇒ CaCl₂ + CO₂ +H₂O
V HCl = 24.65 ml
M HCl = 0.547
mol HCl :
[tex]\tt 24.65\times 0.547=13.48~mlmol[/tex]
ratio mol CaCO₃ : HCl = 1 : 2, so mol CaCO₃ :
[tex]\tt \dfrac{1}{2}\times 13.48=6.74~mlmol=6.74\times 10^{-3}~mol[/tex]
mass of CaCO₃ (MW=100~g/mol) :
[tex]\tt 6.74\times 10^{-3}\times 100=0.674~g=674~mg[/tex]
When 10 Joules of heat are transferred into 30 g of Copper at 18.20oC, the final temperature is 19.07oC. What is the specific heat of copper?
Answer:
c = 0.38 j/g.°C
Explanation:
Given data:
Heat absorbed by copper = 10 j
Mass of copper = 30 g
Initial temperature = 18.20°C
Final temperature = 19.07°C
Specific heat capacity of copper = ?
Solution:
Specific heat capacity:
It is the amount of heat required to raise the temperature of one gram of substance by one degree.
Formula:
Q = m.c. ΔT
Q = amount of heat absorbed or released
m = mass of given substance
c = specific heat capacity of substance
ΔT = change in temperature
ΔT = 19.07°C -18.20°C
ΔT = 0.87 °C
10 J = 30 g×c×0.87 °C
10 J = 26.1 g.°C×c
c = 10 J /26.1 g.°C
c = 0.38 j/g.°C
what is the mass of 16.6 x 10^23 molecules of barium nitrate
The mass of 16.6 × 10²³ molecules of barium nitrate is 718.7g
The number of moles of a substance can be calculated by dividing the mass by its molar mass. That is;no. of moles = mass(g) ÷ molar mass (g/mol)no. of moles of Ba(NO3)2 = 16.6 × 10²³ ÷ 6.02 × 10²³no. of moles = 2.75 × 10⁰no. of moles = 2.75moles. Molar mass of Ba(NO3)2 = 261.34g/molmass of Ba(NO3)2 = 261.34 × 2.75Mass of Ba(NO3)2 = 718.7gTherefore, the mass of 16.6 × 10²³ molecules of barium nitrate is 718.7g.Learn more at: https://brainly.com/question/15743584?referrer=searchResults
A student uses the periodic table to construct a model that uses a simple diagonal arrow to depict decreasing electronegativity. Where should the arrow point to indicate the lowest electronegativity of all the elements?
Answer:
helium
Explanation:
helium has the highest ionization energy level
An element's ability to attract shared electron thus forming covalent bonds is a measure of it's electronegativity. Hence, in other indicate decreasing level of electronegativity, arrow must point to the left across groups and down along the column.
Electronegativity of elements on the periodic table decreases along the groups on the periodic table with elements, Helium and Fluorine being the most electronegative Along the columns, electronegativity decreases downwards with cesium and francium being the least electronegative.Therefore, the arrow should point from right to left across the group and top to bottom along the columns.
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In order to make 159 ml of a 0.135 M benzoic acid solution, what mass of benzoic acid (C7H6O2) is required?
Answer:
Explanation:
159 mL of .135 M benzoic acid will contain
.159 x .135 = .021465 moles of benzoic acid.
Molecular weight of benzoic acid = 122 gm
grams of .021465 moles = 122 x .021465 = 2.6 grams .
So 2.6 grams of benzoic acid will be required .
A student must prepare 7.00 L of 0.100 M Na2CO3 (106 g/mol). Which is the best procedure for preparing this solution
Answer:
Measure 74.2 g Na2CO3 and add H20 until the final homogeneous solution has a volume of 7.00 L
Explanation:
The best procedure is
Mole of
[tex]Na_2CO_3 = Volume \times molarity\\\\= 7.00 L \times 0.100 mol\\\\[/tex]
= 0.700 mol
The mass of
[tex]Na_2Co_3 = Moles \times molar\ mass \\\\= 0.700 mol \times 106 g/mol[/tex]
= 74.2 g
So as per the above calculation, the option 3 is correct as the solution volume is 7.00 L so the same is to be considered
hence, all other options are wrong
Ammonia's unusually high melting point is the result of:__________
a. dipole-dipole forces.
b. London dispersion forces.
c. hydrogen bonding.
d. covalent bonding.
e. ionic bonding.
Answer:
c. hydrogen bonding.
Explanation:
Hydrogen bonding occurs when hydrogen is covalently bonded to a highly electronegative atom such as oxygen, flourine, nitrogen etc.
Hydrogen bonds are quite strong and are known to lead to elevated boiling points. As a result of hydrogen bonding, ammonia is known to have a high melting and boiling point compared to its relative molecular mass.
Every element in group one has ______________ electron in its outer shell. Every element in group two has _______________ electrons in its outer shell.
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A 13.8 g of zinc is heated to 98.8 c in boiling water and then dropped onto a beaker containing 45.0 g of water at 25.o °C .when the water and metal come to thermal equilibrium the temperature is 27.1°C .what is the specific heat capacity
Answer:
[tex]C_{zinc}=0.400\frac{J}{g\°C}[/tex]
Explanation:
Hello!
In this case, by considering thermodynamics and the temperature of zinc, we can infer it is hot while water is cold, it means that the heat lost by the zinc is gained by the water and we can write:
[tex]Q_{Zn}=-Q_{water}[/tex]
In terms of mass, specific heat and temperatures we can write:
[tex]m_{Zn}C_{Zn}(T_{eq}-T_{Zn})=-m_{water}C_{water}(T_{eq}-T_{water})[/tex]
In such a way, by solving for the specific heat capacity of the zinc we write:
[tex]C_{zinc}=\frac{-m_{water}C_{water}(T_{eq}-T_{water})}{m_{Zn}(T_{eq}-T_{Zn})}[/tex]
Thus, by plugging in the given values we obtain:
[tex]C_{zinc}=\frac{-45.0g*4.184\frac{J}{g\°C}* (27.1\°C-98.8\°C)}{13.8g*(27.1\°C-98.8\°C)}\\\\C_{zinc}=0.400\frac{J}{g\°C}[/tex]
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1. A baseball pitcher won 75% of the games he pitched. If he pitched 43 ballgames, how many games
did he win?
Answer:
He won 32 games.
Explanation:
Another way of expressing 75% is 75/100.
To calculate how many games the baseball pitcher won, we multiply the total of games played (43, in this case) by the percent won:
43 * 75/100 = 32.25 ≅ 32
So the baseball pitcher won 32 games.
write a short paragraph about your daily activities nowadays
Ones day my include eating, resting, exercising. Unfortunately mine included not eating, not sleeping, and not exercising. I lay wife awake on my bed wishing for deaths door to find me sooner than later. I do my chores because if I don’t then my parents may take away the few things I love most. In conclusion, my daily activities include thoughts of “ why am I still alive” and actions of crying, punching ext.
Consider two solutions separated by a semipermeable membrane, as shown in the illustration to the right. The membrane allows the passage of small molecules and ions, but not large molecules like polysaccharides or proteins. Solution A contains a 10% solution composed
of glucose and the protein albumin dissolved in water.
Solution B contains a 5% solution of NaCl in water. Indicate whether each substance in the system would flow into Solution A, Solution B, or neither.
1. Water
2. NaCl
3. glucose
4. Albumin
5. Glucose
Answer:
The correct movement would be -
1. Water - into solution A.
2. NaCl - into solution A.
3. glucose - into Solution B.
4. Albumin - neither.
Explanation:
All the substances are separated by the semipermeable membrane and the semipermeable membrane allows the only small molecule to pass through it. So the movement of the given substance would be -
1. Water - into solution A.
Water molecules are small and can easily pass through the semipermeable membrane as it is given that the solution b has low solute concentration and solution A has high solute concentration. It is known that the movement of the solvent always takes place from low solute concentration to high so the movement of water will be into solution A.
2. NaCl - into solution A.
The movement of small ionic molecule NaCl is always from high to low concentration as it is given that solution B has high concentration than solution A so movement will take place into solution A.
3. glucose - into Solution B.
It is also a small molecule and moves from the high glucose region to the low glucose concentration region, in solution A the concentration of glucose is high than solution B so movement would be into solution B.
4. Albumin - neither.
Albumin is a protein which is macromolecule and large in size to pass through the semipermeable membrane so, albumin move neither solution A nor solution B.
Which statement describes how phase changes can be diagrammed as a substance is heated?
The phase is on the y-axis and the temperature is on the x-axis.
The temperature is on the y-axis and the phase is on the x-axis.
The time is on the y-axis and the temperature is on the x-axis.
The temperature is on the y-axis and the time is on the x-axis.
Answer:
The temperature is on the y-axis and the time is on the x-axis.
Explanation:
Which statement describes how phase changes can be diagrammed as a substance is heated? (D is the answer)
The phase is on the y-axis and the temperature is on the x-axis.
The temperature is on the y-axis and the phase is on the x-axis.
The time is on the y-axis and the temperature is on the x-axis.
The temperature is on the y-axis and the time is on the x-axis.
Which statement describes the appearance of a temperature-vs.-time graph? (C is the answer)
A horizontal line shows that the temperature increases at a constant rate over time.
A vertical line shows that the temperature decreases at a constant rate over time.
Horizontal lines where the temperature is constant during phase changes connect upward-sloping lines where the temperature increases.
Horizontal lines where the temperature increases are connected by upward-sloping lines where the temperature is constant for each phase.
Identify the place which has the highest boiling point of water. Identify the place which has the highest boiling point of water. Denver, Colorado, 5280 feet Death Valley, 282 feet below sea level New Orleans, sea level Mt. Everest, 29035 feet A pressurized passenger jet, 35,000 feet
Answer:
B. because if it was to change so would the amount of wieght that gravity puts on us.
Explanation:
A. might seem right but it's not 35,000 under seal level is the OPPOSITE of 35,000 above sea level.
C. water pressure can change where you are at because of the speed or the type of body of water.
D. it does not make any sense.
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How do you know your cell's are working
Use what you’ve learned about Lewis structures and formal charges to predict which of the following sulfur-containing molecule(s) would be least likely to exist.
SO2
H2S2
SCl2
HS
HSOH
Answer:
its DDDDDDDDDDDDDDDDDD
The structure that is least likely to exist is HS.
Sulfur is an element in group 16. Sulfur is a divalent element that has two lone pairs of electrons. This means that sulfur forms compounds in which it is bonded to two atoms or groups.
All the molecules listed can exist because they consists of structures in which sulfur is bonded to two atoms or groups. The only structure that can not exist is HS because it does not satisfy the valency of sulfur.
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What is the mass of insoluble lead(II) iodide (461.0 g/mol) produced from 0.830 g of potassium iodide (166.00 g/mol) and aqueous lead(II) nitrate?A) 4.61 g. B) 0.149 g.C) 2.31 g.D) 1.15 g.E) 0.598 g.
Answer:
C
Explanation:
The mass of insoluble lead iodide produced from 0.830 g of potassium iodide in a reaction with lead nitrate is 2.31 g. Thus option C is correct.
What is lead iodide?Lead iodide or PbI is an ionic compound formed from the ionic bonding between metal lead and iodine. It is industrially prepared from the reaction of aqueous lead nitrate with potassium iodide.
Potassium iodide easily reacts with lead iodide as per the reaction written below:
[tex]\rm KI + PbNO_{3} \rightarrow KNO_{3} + PbI[/tex]
As per this reaction one mole of potassium iodide produce one mole of lead iodide. The molar mass of potassium iodide is 166 g/mol and that of lead iodide is 461 g/mol.
Thus, 166 g of potassium iodide gives 461 g of lead iodide. The mass of lead iodide then produced from 0.830 g of potassium iodide is calculated as follows:
mass = (0.830 g × 461)/ 166
= 2.31 g.
Hence, the mass of insoluble lead iodide produced from 0.830 g of potassium iodide in a reaction with lead nitrate is 2.31 g and option C is correct.
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Which chemical equation is balanced? OCH4 + O2 + H2O + CO2 OCH4 + O2 + 2H2O + CO2 O 6 CH4 + O2 + 2H2O + 2 CO2 OCH4 + 202 + 2H2O + CO2
Answer:
CH₄ + 2O₂ → 2H₂O + CO₂
Explanation:
Chemical equation:
CH₄ + O₂ → H₂O + CO₂
Balanced chemical equation:
CH₄ + 2O₂ → 2H₂O + CO₂
Option d is correct option.
1st step:
CH₄ + O₂ → H₂O + CO₂
Left hand side Right hand side
C = 1 C = 1
H = 4 H = 2
O = 2 O = 3
Step 2:
CH₄ + O₂ → 2H₂O + CO₂
Left hand side Right hand side
C = 1 C = 1
H = 4 H = 4
O = 2 O = 4
Step 3:
CH₄ + 2O₂ → 2H₂O + CO₂
Left hand side Right hand side
C = 1 C = 1
H = 4 H = 4
O = 4 O = 4
An airplane weighing 80,000. kg at takeoff reaches a speed of 880 km/h. What is the de Broglie wavelength in meters of the plane?
Answer:
3.39 * 10^-41 m
Explanation:
Given that:
speed of airplane = 880 km/hr
Mass of airplane = 80000 kg
Debroglie wavelength (λ) = h / mv
h = planck's constant = 6.626 * 10^-34
; mass = 80000kg
Velocity = 880km/hr to convert to m/s
Velocity = (880 * 1000m) / 3600 =244.44 m / s
λ = (6.626 * 10^-34) /(80000*244.44)
λ = (6.626 * 10^-34) / 19555200
λ = 3.3889 *10^-41
λ = 3.39 * 10^-41 m
do seeds need energy to germinate
Answer:
Seeds need oxygen so that they can produce energy for germination and growth. The embryo gets energy by breaking down its food stores. Like all organisms, this is done through a process known as aerobic respiration. —a series of reactions where energy is released from glucose, using oxygen.
A cube of iron and a cube of wood, each having a volume of V = 3.25 10-4 m3, are each placed in a large beaker of water. The density of the wood is rhowood = 3.73 102 kg/m3 and the density of the iron is rhoiron = 7.86 103 kg/m3. Calculate the buoyant force on each. (The cube of wood is allowed to float at the surface.)
Answer:
anor277
Nov 17, 2017
Well, by definition,
Molarity
≡
Moles of solute
Volume of solution
Explanation:
And thus...
moles of solute
=
molarity
×
volume
We use a molar quantity of
80.3
⋅
g
174.01
⋅
g
⋅
m
o
l
−
1
=
0.461
⋅
m
o
l
with respect to
potassium sulfate
And thus
volume
=
moles of solute
molarity
80.3
⋅
g
174.01
⋅
g
⋅
m
o
l
−
1
3.12
⋅
m
o
l
⋅
L
−
1
=
0.148
⋅
L
.
The buoyant force is one that acts against the weight of an object suspended in a fluid. The value of the buoyant force on each are:
i. Buoyant force on the cube of iron = 25.0 N
ii. Buoyant force on the cube of wood = 1.20 N
Upthrust is a force which acts against the direction of the weight of an object when suspended in a fluid. It acts majorly upwards against gravity, and it can be referred to as a buoyant force.
The amount of upthrust on object in a fluid sometimes depends on the density, volume and gravity acting on the object.
So that;
Upthrust = density x volume x gravity
Thus from the given question;
i. The buoyant force on the cube of iron can be determined by:
Upthrust = 7.86 x [tex]10^{3}[/tex] * 3.25 x [tex]10^{-4}[/tex] * 9.8
= 25.034
Upthrust = 25.0 N
Therefore, the buoyant force on the cube of iron is 25.0 N.
ii. The buoyant force on the cube of wood can be determined by:
Upthrust = 3.73 x [tex]10^{2}[/tex] * 3.25 x [tex]10^{-4}[/tex] * 9.8
= 1.1880
Upthrust = 1.20 N
Therefore, the buoyant force on the cube of wood is 1.20 N.
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empirical formula for
Ca 40.078 22.3%
As 74.9216 41.6%
O 15.9994 35.6%
H 1.00794 0.560%
The empirical formula : CaAsO₄H
Further explanationThe empirical formula is the smallest comparison of atoms of compound =mole ratio of the components
The principle of determining empirical formula
Determine the mass ratio of the constituent elements of the compound. Determine the mole ratio by by dividing the percentage by the atomic mass Ca[tex]\tt \dfrac{22.3}{40.078}=0.556[/tex]
As[tex]\tt \dfrac{41.6}{74.9246}=0.555[/tex]
O[tex]\tt \dfrac{35.6}{15.9994}=2.225[/tex]
H[tex]\tt \dfrac{0.56}{1.00794}=0.556[/tex]
Divide by the smallest ratio(0.555) :
Ca : As : O : H ⇒
[tex]\tt \dfrac{0.556}{0.555}\div \dfrac{0.555}{0.555}\div \dfrac{2.225}{0.555}\div \dfrac{0.556}{0.555}=1\div 1\div 4\div 1[/tex]
A patient provides a urine sample. The density of the patient's urine is 1.0192 g/mL. What is the specific gravity of the urine?
Answer:
1.092
Explanation:
Density = 1.0192 g/mL
oecific gravity = ?
Specific gravity is the ratio of a material's density with that of water.
The density of water at 4 degrees Celsius = 1 g/mL
Specific gravity = 1.0192 / 1 = 1.0192
Because specific gravity is a ratio, it has no dimension.