Answer:
2.8 x10^-4
Explanation:
what problems occurs if the firework mixture is not pure(they are dirty or contaminated?
Firework mixture is made up with potassium nitrate and other toxic chemicals. They produce harmful wastes to the atmosphere. If they are contaminated, they make release very dangerous explosives by unwanted reactions.
What are explosives?Explosives are chemicals releasing lot of heat energy to the surrounding upon decomposition. Nitrogen compounds, hydrogen etc are explosive and they will explode in air or water.
Chemicals have to handled carefully and stored as per the conditions based on their chemical and physical properties. Some of them may easily corrode. Some may rapidly reacts with water or air and some may explode in air.
Explosive chemicals causes atmospheric pollution as well as health risk by releasing hazardous chemicals. If they are contaminated then there may occur some unwanted reaction and it will make the risk intense by producing toxic gases.
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A-potassium
B-lead
C-iron
D-magnesium
E-zinc
The unknown substance : Lead
Further explanationGiven
Density of element
mass of unknown substance = 40 g
volume = 3.5 cm³
Required
The density of unknown substance
Solution
Density is the ratio of mass per unit volume
The unit of density can be expressed in g/cm³ or kg/m³
Density formula:
[tex]\large {\boxed {\bold {\rho ~ = ~ \frac {m} {V}}}}[/tex]
Input the value to find the density of an unknown substance :
ρ = 40 g : 3.5 cm³
ρ = 11.43 g/cm³
If we look at the table, the substance which has a density of 11.43 is Lead
What is the relationship between the period number and the number of valence electrons?
Answer: Across each row, or period, of the periodic table, the number of valence electrons in groups 1–2 and 13–18 increases by one from one element to the next. Within each column, or group, of the table, all the elements have the same number of valence electrons.
Relationship between the period number and the number of valence electrons:
There are total 7 period in a periodic table.Valence electrons can be also determined as electrons in the outermost shell.The number of valence electrons in an atom is reflected by its position in the periodic table of the elements.Across each row, or period, of the periodic table, the number of valence electrons in groups 1-2 and 13-18 increases by one from one element to the next.For example: Group 17 has 7 valence electrons which is one less to the next group number i.e. 18.Within each column, or group, of the table, all the elements have the same number of valence electrons.Learn more:
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Which of these statements is true?
A.The neutrons have a neutral charge and help stabilize an atom
B.The electrons have a negative charge and are in the nucleus
C.The protons have a negative charge and are in the nucleus
D.The electrons have a positive charge and orbit the nucleus in the electron cloud
Answer:
Among these statements B is the correct answer.
One electron(s) are added to an phosphorus atom. Enter the chemical symbol of the element.
Answer:
S (sulphur)
Explanation:
In a neutral atom, the number of electrons and the number of protons in an element are equal. These numbers are called the ATOMIC NUMBER. That is, in a neutral atom;
proton no. = electron no. = Atomic no.
Hence, in this case where phosphorus atom has an electron number of 15. It means that there are 15 protons and 15 electrons in a phosphorus atom. If one electron is added to these electrons i.e. 15 +1, there will be 16 electrons in the atom, hence, this atom becomes SULPHUR element, which has 16 electrons in its atom, with chemical symbol S.
an oxygen tank used for scuba diving has. avolume of 12.0 L .If the pressure of the tank is known to be 204.047 atm and the temperature is 22.0 C(295 K), how many moles of oxygen are contained in the tank
Answer: 101 moles of oxygen are contained in the tank
Explanation:
According to ideal gas equation:
[tex]PV=nRT[/tex]
P = pressure of gas = 204.047 atm
V = Volume of gas = 12.0 L
n = number of moles = ?
R = gas constant =[tex]0.0821Latm/Kmol[/tex]
T =temperature =[tex]22.0^0C=(22.0+273)K=295K[/tex]
[tex]n=\frac{PV}{RT}[/tex]
[tex]n=\frac{204.047atm\times 12.0L}{0.0821 L atm/K mol\times 295K}=101moles[/tex]
Thus 101 moles of oxygen are contained in the tank
HURRY
Fill in the blank -
metals like to _ electrons to form ionic bonds
Which of the following is a true statement about wind erosion?
Most wind erosion happens in the Arctic.
Most wind erosion happens in deserts, beaches, and plowed fields.
Most wind erosion happens only on top of mountains.
Most wind erosion happens in areas with tropical climate.
Answer :
B. Most wind erosion happens in deserts, beaches, and plowed fields.
What is the charge of an element with 15 protons, 19 neutrons and 18 electrons?
Answer:
negative
Explanation:
18 negative
19 neutral
10 positive
there are are more negative
blank is the total disappearance of all members of a species.
Answer:
Extinction
Explanation:
When a species becomes extinct, every last specimen has died out
an orbital is a region in an atom where there is a high probability of finding _________
A) an alpha particle
B) a neutron
C) an electron
D) a positron
Answer:
its electron
Explanation:
i dont have an explanation but i hope you get it right
pls help asap!!
The surface of earth has many impact craters that have been filled in with sediment. these craters were created by
A. moles
B. dinosaurs
C. people
D. meteorites
Answer:
D
Explanation:
Craters produced by the collision of a meteorite with the Earth (or another planet or moon) are called impact craters. The high-speed impact of a large meteorite compresses, or forces downward, a wide area of rock. The pressure pulverizes the rock.
CHEMISTRY HELP!! due in 10 minutes! :(
Answer:
Yes, because it match the octet rule!!
It is double bond lewis structure of ch2s!!
Explanation:
Which feature do all adult echinoderms have?
O moveable spine
O muscular foot
O mantle
O endoskeleton
Answer:
endoskeleton i think
Explanation:
Using standard heats of formation, calculate the standard enthalpy change for the following reaction. 2NH3(g) 3N2O(g)4N2(g) 3H2O(g) ANSWER: kJ Submit Answer
Answer: [tex]\Delta H^{0} = -879.15 kJ/mol[/tex]
Explanation: Heats of formation is the amount of heat necessary to create 1 mol of a compound from its molecular constituents. The basic conditions the substance is formed is at standard conditions: 1 atm and 25°C. Each compound has its own heat of formation per mol of compound (kJ/mol), but to an element is assigned a value of zero.
Standard Enthalpy Change is defined as the heat absorbed or released when a reaction takes place. It can be positive or negative, which means reaction is endothermic or exothermic, respectively.
Enthalpy change is calculated as the difference between the sum of heat formation of products and the sum of heat formation of the reactants:
[tex]\Delta H^{0}=\Sigma H^{0}_{f}_{(products)}-\Sigma H^{0}_{f}_{(reactants)}[/tex]
For the reaction
2NH₃ + 3N₂O → 4N₂ + 3H₂O
2(-46.2) + 3(82.05) 4(0) + 3(-241.8)
[tex]\Delta H^{0}=3(-241.8)-[ 2(-46.2)+3(82.05)][/tex]
[tex]\Delta H^{0}=-725.4-153.75[/tex]
[tex]\Delta H^{0}=-879.15[/tex]
The standard enthalpy change for the reaction is [tex]\Delta H^{0}=-879.15[/tex] kJ
Which best explains why male whitetail deer grow antlers but females seldom grow antlers?
Answer: I'm not sure if you have a selection of choice but I think it's A. Female deer have no need for antlers.
Explanation: I mean they don't.. Even if the Male are older that doesn't stop a female deer from growing antlers.. Just flimsy one's I guess.
In an ecosystem, as the growth of antlers is controlled by genes male male whitetail deer grow antlers but females seldom grow antlers.
What is an ecosystem?Ecosystem is defined as a system which consists of all living organisms and the physical components with which the living beings interact. The abiotic and biotic components are linked to each other through nutrient cycles and flow of energy.
Energy enters the system through the process of photosynthesis .Animals play an important role in transfer of energy as they feed on each other.As a result of this transfer of matter and energy takes place through the system .Living organisms also influence the quantity of biomass present.By decomposition of dead plants and animals by microbes nutrients are released back in to the soil.
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Rank the following compounds in order of decreasing boiling point: potassium fluoride (KF), acetylene (C2H2), and formaldehyde (CH2O)
Answer: [tex]KF[/tex] > [tex]CH_2O[/tex] > [tex]C_2H_2[/tex]
Explanation:
The order of boiling point depends upon the type of interactions present between the molecules.
Potassium fluoride (KF) is an ionic compound and the opposite ions are held together by strong electrostatic forces.
[tex]C_2H_2[/tex] is a covalent compound and the molecules are held together by weak van der Waals' forces.
Formaldehyde is a polar compound due to presence of polar carbonyl group. Hence dipole-dipole force is present between formaldehyde molecules.
Thus the decreasing order of boiling point is:
[tex]KF[/tex] > [tex]CH_2O[/tex] > [tex]C_2H_2[/tex]
A certain liquid X has a normal boiling point of 133.60°C and a boiling point elevation constant Kb= 2.46°C kg mol^-1.Calculate the bolling point of a solution made of 52.2g of benzamide (C7H7NO) dissolved in 350. g of X.
Answer:
136.63 °C
Explanation:
ΔTb=Tb solution - Tb pure
Where; Tb pure = 133.60°C
molar mass of solute = 121.14 g/mol
number of moles of solute; 52.2g/121.14 g/mol = 0.431 moles
molality = 0.431 moles/350 * 10^-3 = 1.23 molal
Then;
ΔTb = Kb * m * i
Kb = 2.46°C kg mol^-1
m = 1.23 molal
i = 1
ΔTb = 2.46 * 1.23 * 1
ΔTb = 3.03 °C
Hence;
Tb solution = ΔTb + Tb pure
Tb solution = 3.03 °C + 133.60°C
Tb solution = 136.63 °C
3 H2 (g) + N2 (g) 2 NH3 (g)
1.36 liters of hydrogen gas will produce how many grams of NH3 at STP?
Answer:
Mass = 0.697 g
Explanation:
Given data:
Volume of hydrogen = 1.36 L
Mass of ammonia produced = ?
Temperature = standard = 273.15 K
Pressure = standard = 1 atm
Solution:
Chemical equation:
3H₂ + N₂ → 2NH₃
First of all we will calculate the number of moles of hydrogen:
PV = nRT
R = general gas constant = 0.0821 atm.L/mol.K
1atm ×1.36 L = n × 0.0821 atm.L/mol.K × 273.15 K
1.36 atm.L = n × 22.43 atm.L/mol
n = 1.36 atm.L / 22.43 atm.L/mol
n = 0.061 mol
Now we will compare the moles of hydrogen and ammonia:
H₂ : NH₃
3 : 2
0.061 : 2/3×0.061 = 0.041
Mass of ammonia:
Mass = number of moles × molar mass
Mass = 0.041 mol × 17 g/mol
Mass = 0.697 g
A student fails to insert the cuvette into the colorimeter or spectrophotometer correctly. What effect will this have on the measured absorbance
Answer:
It would cause scattering of light and absorbance measurement is going to be reported as too large
Explanation:
The curvette was not inserted correctly into the spectrometer. The effect that this would have on measured absorbance is that it would cause scattering of light.
Failing to line the curvette correctly would cause light to scatter, the light reaching the photodetector would be less. This less light would then be interpreted as more light being absorbed. This would end up making the absorbance value to be read as too large.
What is the mass of 1.33 moles of Ba3(PO4)2?
Choices:
108 g
801 g
659 g
801 mol
Please help :(
Answer:
801 g
Explanation:
From the question given above, the following data were obtained:
Number of mole of Ba₃(PO₄)₂ = 1.33 moles
Mass of Ba₃(PO₄)₂ =?
Next, we shall determine the molar mass of Ba₃(PO₄)₂. This can be obtained as follow:
Molar mass of Ba₃(PO₄)₂ = (137.3×3) + 2[31 + (4×16)]
= 411.9 + 2[31 + 64]
= 411.9 + 2[95]
= 411.9 + 190
Molar mass of Ba₃(PO₄)₂ = 601.9 g/mol
Finally, we shall determine the mass of Ba₃(PO₄)₂. This can be obtained as follow:
Number of mole of Ba₃(PO₄)₂ = 1.33 moles
Molar mass of Ba₃(PO₄)₂ = 601.9 g/mol
Mass of Ba₃(PO₄)₂ =?
Mole = mass /Molar mass
1.33 = Mass of Ba₃(PO₄)₂ / 601.9
Cross multiply
Mass of Ba₃(PO₄)₂ = 1.33 × 601.9
Mass of Ba₃(PO₄)₂ = 801 g
The process by which cells divide is called
A
O replication
B.
mitosis
C.
respiration
D.
photosynthesis
the answer is mitosis
How do you think the periodic table helps us better understand our world?
Answer:
The periodic table helps organize all the elements found in the world and tells a great deal of information on each of the elements such as their atomic mass, symbol, atomic number, and more. It even is organized into groups (columns) and periods (rows). The elements in the same group mostly have similar chemical properties. In short, the periodic table is a list of the elements that make up the world around you.
Explanation:
PLZ HELP ME!!!!!! BEING TIMED!!!!!
Answer:
3 one
Explanation:
Chemical bonds between atoms in molecules such as H2, CH4, NH3, and
many large biological molecules are:
lonic Bonds
Hydrogen Bonds
Covalent Bonds
Metallic Bonds
Answer:In ionic compounds, electrons are transferred between atoms of different elements to form ions. But this is not the only way that compounds can be formed. Atoms can also make chemical bonds by sharing electrons equally between each other. Such bonds are called covalent bonds. Covalent bonds are formed between two atoms when both have similar tendencies to attract electrons to themselves (i.e., when both atoms have identical or fairly similar ionization energies and electron affinities). For example, two hydrogen atoms bond covalently to form an H2 molecule; each hydrogen atom in the H2 molecule has two electrons stabilizing it, giving each atom the same number of valence electrons as the noble gas He.
Compounds that contain covalent bonds exhibit different physical properties than ionic compounds. Because the attraction between molecules, which are electrically neutral, is weaker than that between electrically charged ions, covalent compounds generally have much lower melting and boiling points than ionic compounds. In fact, many covalent compounds are liquids or gases at room temperature, and, in their solid states, they are typically much softer than ionic solids. Furthermore, whereas ionic compounds are good conductors of electricity when dissolved in water, most covalent compounds are insoluble in water; since they are electrically neutral, they are poor conductors of electricity in any state.
How many moles are in 1.5 x 10^23 atoms of fluorine?
Answer: 0.125 moles F2
Explanation: 1.5x1023 atoms of F = 0.75x10^23 molecules F2
moles F2 = 0.75x10^23/avogadro number = 0.125 moles
There are 0.25 moles in 1.5 x [tex]10^{23}[/tex] atoms of fluorine.
Given,
How many moles are in one atom?
In one mole we have,
6.02 x [tex]10^{23}[/tex] atoms.
1 mole = 6.02 x [tex]10^{23}[/tex] atoms
Find the number of moles in 1.5 x [tex]10^{23}[/tex] atoms of fluorine.
We have,
1 mole = 6.02 x [tex]10^{23}[/tex] atoms
Multiply 1.5 x [tex]10^{23}[/tex] / 6.02 x [tex]10^{23}[/tex] on both sides
1.5 x [tex]10^{23}[/tex] / 6.02 x [tex]10^{23}[/tex] x 1 mole = 1.5 x [tex]10^{23}[/tex] / 6.02 x [tex]10^{23}[/tex] x 6.02 x [tex]10^{23}[/tex] atoms
1.5/6.02 mole = 1.5 x [tex]10^{23}[/tex] atoms
0.25 moles = 1.5 x [tex]10^{23}[/tex] atoms.
Thus there are 0.25 moles in 1.5 x [tex]10^{23}[/tex] atoms of fluorine.
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25.
Chemical equations should be balanced so that they demonstrate the Law of Conservation of Mass. Which statement about balanced chemical equations is correct?
A
The products must contain the same number and types of atoms as the reactants.
B. The products must contain the same arrangement of atoms as found in the reactants,
C. The products must contain the same number but not the same types of atoms as the reactants.
D. The products must contain the same types but not the same numbers of atoms as the reactants,
Answer:
a
Explanation:
they have to have the same numbers on each side.
According to the law of conservation of mass, the total mass in the product side is equal to the mass in the reactant side of a reaction. Thus, option A that is The products must contain the same number and same types of atoms as the reactants is correct.
What is mass conservation?Mass conservation is similar to law of energy conservation. That is mass can neither be created nor be destroyed. Thus The total mass in a system is conserved. Therefore,in reaction the mass of product have to be equal to the mass of reactant.
A balanced reaction represent all reactants in their state and in perfect stoichiometry. Hence, each elements have to be equal in number on both side. No new atoms is created here and no atom is lost.Same number and same type will be in both side.
During a chemical reaction, the regrouping of atoms occurs to form the new product. Hence, no new atoms are added . Therefore The products must contain the same number and same types of atoms as the reactants and satisfies the mass conservation.
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What is the name for a particle that has a mass about 1/1835 of a proton, but with a negative charge
Answer:
Electron
Explanation:
assume you mix 0.71g of chlorine with 1.00g of fluorine in a 258 ml flask at 23 . what is the partial pressure of each gas
Answer:
See explanation
Explanation:
Number of moles of Cl2 = 0.71g/71g/mol = 0.01 moles
Number of moles = 1.0 g/38g/mol = 0.02 moles
Total = 0.01 + 0.02 = 0.03 moles
From the ideal gas equation;
PV=nRT
P=?
V= 258 ml
n= 0.03 moles
T= 296 K
P= nRT/ V
P= 0.03 × 0.082 × 296/258
P= 0.003 atm
Partial pressure Cl2 = 0.01/0.03 × 0.003 atm = 0.001 atm
Partial pressure = F2 = 0.02/0.03 × 0.003atm = 0.002 atm
In Universe L, recently discovered by an intrepid team of chemists who also happen to have studied interdimensional travel, quantum mechanics works just as it does in our universe, except that there are three d orbitals instead of the usual number we observe here. Use these facts to write the ground-state electron configurations of the second and third elements in the first transition series in Universe.
Answer:
Second element(Titanium); [Ar] 3d2 4s2
Third element(Vanadium):Ar 3d3 4s2
Explanation:
Given that there are only three d orbitals in universe L instead of five, the electronic configuration of the second and third elements in the first transition series will now look thus;
Second element(Titanium); [Ar] 3d2 4s2
Third transition element(Vanadium):Ar 3d3 4s2
Hence, the electronic configuration of Titanium and Vanadium in universe L is just the same as what it is on earth.