Answer:
if you are working with a substances that produce or generate toxic or harmful fumes, vapours, gases, dust or chemical aerosols
it should be carried out in a fume cupboard to eliminate or reduce the risk of exposure to an acceptable and safe level.
NEED HELP ASAP PLEASE HELP
Answer:
I think it's A not D or C maybe B probably A
25 atoms W mass in grams
Answer The mass in grams for 25 atoms W is 763.10e-23.
The W is a symbol of tungsten. 25 atoms of tungsten gives 4596 mass in gram.
What are atoms?Atoms can be defined as the smallest unit into which matter can be divided without release of electrically charged particle. It is the smallest unit that form chemical elements.
Atoms are made up of electron, protons and neutrons.
To calculate mass in gram for an atom is
Mass in gram = number of atoms x atomic mass
Atomic mass of W i.e. tungsten is 183.84 u.
So mass in gram of W = 25 atoms x 183.84 u
= 4596 g
Thus, W is a symbol of tungsten. 25 atoms of tungsten gives 4596 mass in gram.
To learn more about atoms, refer to the link below:
https://brainly.com/question/1566330
#SPJ2
4. Chemical formula, mg (Cl0₃)2
a) calculate the number of moles for 3.24g, Mg (Cl03)2
b) calculate the molarity of mg (Cl03)2 if all of it were dissolved in
5.08 L distilled water.
Answer:
0.017mole
0.0033M
Explanation:
Given parameters:
Formula of the compound:
Mg(ClO₃)₂
Mass of the sample = 3.24g
Unknown:
Number of moles of the sample = ?
Molarity = ?
Solution:
The number of moles of any substance is given as:
Number of moles = [tex]\frac{mass}{volume}[/tex]
Molar mass of Mg(ClO₃)₂ = 24 + 2[35.5 + 3(16)] = 191g/mol
Number of moles = [tex]\frac{3.24}{191}[/tex] = 0.017mole
Molarity is the number of moles of a solute in a solution:
Molarity = [tex]\frac{number of moles }{volume}[/tex]
Volume given = 5.08L
Molarity = [tex]\frac{0.017}{5.08}[/tex] = 0.0033M
Crystallization of sodium acetate occurs spontaneously from a supersaturated solution. What can you deduce about the signs of ΔS and ΔH for this process?
Answer:
ΔS < 0
ΔH < 0
Explanation:
Recall that the process is crystallization. Crystallization involves conversion of aqueous ions back to solid. This process decreases the entropy of the system hence ΔS is negative.
But remember that a process is only spontaneous when ΔG <0 (negative). From;
ΔG = ΔH - TΔS
If ΔS is negative, then (-TΔS) must be positive since ΔS is negative. The only way to make the process spontaneous is to make ΔH negative so that ΔG also becomes negative.
Calculate ΔS∘rxn for the following reaction. The ΔS∘ for each species is shown below the reaction.
C2H2(g) + 2H2(g) → C2H6(g)
S∘(J/mol⋅K) 200.9 130.7 229.2
A) -159.0 J/K
B) -233.1 J/K
C) +233.1 J/K
D) 303.3 J/K
E) 560.8 J/K
Answer:
-233.1 J/K
Explanation:
The standard entropy change for the reaction C₂H₂(g) + 2 H₂(g) → C₂H₆(g), is B) -233.1 J/K.
Let's consider the following balanced equation.
C₂H₂(g) + 2 H₂(g) → C₂H₆(g)
Entropy is a measure of how much the energy of atoms and molecules becomes more spread out in a process. We can calculate the standard entropy change for the reaction (ΔS°rxn) using the following expression.
[tex]\Delta S \°_{rxn} = \Sigma n_p \times S_p\° - \Sigma n_r \times S_r\°[/tex]
where,
n: molesS°: standard entropy of the speciesp: productsr: reactants[tex]\Delta S \°_{rxn} = 1 mol \times S\°(C_2H_6) - 1 mol \times S\°(C_2H_2) - 2 mol \times S\°(H_2)\\\Delta S \°_{rxn} = 1 mol \times (229.2J/mol.K) - 1 mol \times (200.9J/K.mol) - 2 mol \times (130.7J/K.mol) = -233.1 J/K[/tex]
The standard entropy change for the reaction C₂H₂(g) + 2 H₂(g) → C₂H₆(g), is B) -233.1 J/K.
Learn more here: https://brainly.com/question/13146879
When a solution is allowed to crystallize slowly, impurities are excluded from the growing crystal structure because: A. The molecules in the crystal lattice are cooler than the solvent and impurities would have too high a melting point to join the lattice.B. The molecules in the crystal lattice are in equilibrium with the molecules in solution and molecules that don't fit well into the lattice (impurities) are likely to return to the solution.C. Impurities could never join the lattice because they are always liquid at room temperature.D. During slow crystallization, impurities are prevented from joining the crystal structure because of their ionic strength.
Answer:
B
Explanation:
An element with the electron configuration: [noble gas] ns2 (n - 1)d10 np3 has how many_____________ valence electrons.
a. 2
b. 15
c. 3
d. 10
e. 5
Answer:
The correct option is e. 5
Explanation:
An element with the electron configuration [noble gas] ns² (n - 1)d¹⁰ np³ belongs to the nitrogen group element - group 15 - in a period higher than 2. The element could be As, Sb or Bi. For example, arsenic (As) has the electron configuration [Ne] 4s² 3d¹⁰ 4p³.
The valence electrons are those in the highest energy level, in a s or p sublevel. For the elements with the general electron configuration [noble gas] ns² (n - 1)d¹⁰ np³ has 5 valence electrons: 2 electrons in a s sublevel and 3 electrons in a p sublevel. The electrons in the d orbital are in a lowest energy level (n-1).
Therefore, the correct option is e. 5.
Small changes in _________ protein structure may lead to big changes in _________ protein structures.
A. secondary; tertiary
B. primary; secondary
C. primary; tertiary
D. tertiary; secondary
Answer:
B. primary; secondary
Explanation:
Small changes in primary structure can result in large changes in protein shape and function. Secondary structure describes regions where the polypeptide is folded into localized shapes. There are two types of secondary structure (alpha helix and Beta pleated sheet).
The process of cells dividing into two identical cells is called?
Answer:
mitosis
Explanation:
How many moles of calcium chloride are needed to produce 6.50 moles of sodium chloride?
Answer:
This question appear incomplete
Explanation:
This question appear incomplete because an equation to show the production of sodium chloride from calcium chloride should have been illustrated. However, if the balanced chemical equation showing sodium chloride (NaCl) been a product of a reaction involving calcium chloride (CaCl₂) as a reactant (shown below) is to be used, then we start by writing a complete balanced chemical equation
CaCl₂ + Na₂CO₃ ⇒ CaCO₃ + 2NaCl
From the equation above, it can be deduced that 1 mole of CaCl₂ is required to produce 2 moles of NaCl, thus how many moles of CaCl₂ will be required to produce 6.5 moles of NaCl.
1 mole of CaCl₂ = 2 moles of NaCl
? moles of CaCl₂ = 6.5 moles of NaCl
cross multiply
? moles of CaCl₂ = 6.5 × 1/2
? moles of CaCl₂ = 3.25 moles of CaCl₂
3.25 moles of CaCl₂ will be needed to produce 6.5 moles of NaCl
Identify when an object has a kinetic energy of zero joules.
Question 2 options:
A. as a pendulum swings downward.
B. when the energy has been destroyed.
C. just after a ball it leaves your hand pitching a ball.
D. when an object is no longer in motion.
Answer:
D I think
Explanation:
cuz 0 j means there is nothing moving
Answer:
D. when an object is no longer in motion.
Explanation:
Which best explains why an iceberg floats?
Water expands and becomes denser when it freezes.
Water contracts and becomes denser when it freezes.
Answer:
The options to this question are incomplete. The remaining two options are:
C. Water expands and becomes less dense when it freezes.
D. Water contracts and becomes less dense when it freezes.
The answer is C. Water expands and becomes less dense when it freezes.
Explanation:
Water is a chemical compound that exists in the three states of matter viz: solid as ICE, gas as vapour and liquid as WATER. However, due to the DENSITY properties of each state, ice floats on water. Ice is less dense than water.
When liquid water freezes, it's particles expands i.e increases in volume. Hence, it becomes less dense than water. This causes an iceberg to float on water because it has a lesser density compared to the liquid water caused by an expansion of its particles.
Answer:
answer is c
Explanation:
To measure the amount of chlorine in a well-boring fluid, an analytical chemist adds silver nitrate solution to a sample of the fluid and collects the solid silver chloride product. When no more is produced, she filters, washes and weighs it, and finds that has been produced. The balanced chemical equation for the reaction is:Cl(aq) + AgNO3(ag)------- AgCl(s) + NO3- (ag) o What kind of reaction is this? a. acid-base b. redox orvcap c. precipitation
Answer:
c. precipitation
Explanation:
Let's consider the following balanced net ionic equation.
Cl⁻(aq) + AgNO₃(ag) ⇒ AgCl(s) + NO₃⁻ (ag)
What kind of reaction is this?
a. acid-base. No, because the reactants are not acids and bases.
b. redox. No, because all the species have the same oxidation numbers in the reactants and the products
c. precipitation. Yes, because an insoluble compound (AgCl) is produced, which then precipitates.
What is the volume of 2.0 moles of N2?
Answer:
1.2506
Explanation:
What does the reduction potential chart tell you about two elements?
A. Where they are located on the periodic table
B. Which is more likely to be reduced
C. Which forms a positive ion
D. Which one is a metal
Answer:
which is more likely to be reduced
Explanation:
Answer:
B
Explanation:
Calculate the mass percent for a solution containing 85g NaCl and 155g water.
The mass percent for a solution : 35.42%
Further explanationThe concentration of a substance can be expressed in several quantities such as moles, percent (%) weight/volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.
[tex]\tt \%mass=\dfrac{mass~solute}{mass~solution}\times 100\%[/tex]
mass solute = 85 g
mass solution = 85 + 155 = 240 g
[tex]\tt \%mass=\dfrac{85}{240}\times 100\%=35.42\%[/tex]
A cell in the leaf of a corn plant contains more chloroplasts than a cell in the stem of a corn plant. Based on this observation, it can be inferred that, when compared to the cell in the stem, the cell in the leaf
Answer:
This question lacks options, the options are:
A). synthesizes more sugar
B). has a higher chromosome count
C). produces fewer proteins
D). uses less carbon dioxide
The answer is A
Explanation:
The chloroplast is an organelle present in the cells of photosynthetic organisms. It is the site where photosynthesis, which is the production of food (sugars) from sunlight energy, occurs.
According to this question, a cell in the leaf of a corn plant contains more chloroplasts than a cell in the stem of the same corn plant. Based on this observation, it can be inferred that the LEAF CELLS WILL SYNTHESIZE MORE SUGARS THAN THE STEM CELL because the more the chloroplast, the higher the photosynthetic rate and subsequently the higher the amount of sugar produced.
The amount of energy required to raise the temperature of 1 kilogram of a substance by 1 kelvin is called its
I hope it'll help
thanks...
why PbS is less soluble in water
Answer:
PbS shows a very low solubility in water, and it is insoluble in organic solvents. Any "dissolution" process in acids (hydrochloric acid, nitric acid, aqua regia) is accompanied with a chemical reaction whereby H2S is liberated and the corresponding soluble Pb2+ salts are formed. hope that helps
In the common lead storage battery used in automobiles, the following two half-reactions occur in acid solution:
Oxidation Pb(s)+HSO−4(aq) → PbSO4(s)
Reduction PbO2(s)+HSO−4(aq) → PbSO4(s).
Write a balanced equation for the overall battery reaction.
Explanation:
Common Lead Storage Battery Used In Automobiles, The Following Two Half-reactions Occur In Acid Solution: Oxidation Pb(s)+HSO−4(aq) → PbSO4(s) Reduction PbO2(s)+HSO−4(aq) → PbSO4(s). Write A Balanced Equation For The Overall Battery Reaction.
You add 10.00 mL of 0.200 M NaOH to 50.00 mL of pure water, and to this mixture you then add 5.00 mL of 0.100 HCl. What will be the pH of the resulting solution?
Answer:
Need ko point salamat mamaya ko yan sagutin d jowklang
28.00mL
What mass of precipitate can form if 1.5 L of a saturated solution of Pb(NO3)2 is mixed with 0.765 L of a 0.205 M NaI solution?
Answer:
[tex]m_{PbI_2}=36.2gPbI_2[/tex]
Explanation:
Hello!
In this case, since the chemical reaction that takes place when Pb(NO3)2 and NaI are mixed is:
[tex]Pb(NO_3)_2(aq)+2NaI(aq)\rightarrow PbI_2(s)+2NaNO_3(aq)[/tex]
By which a solid precipitate of PbI2 is produced. In such a way, since we know the volume and molarity of NaI, we can compute the moles of NaI as shown below:
[tex]n_{NaI}=0.765L*0.205\frac{molNaI}{L}=0.157molNaI[/tex]
Next, since it is in a 2:1 mole ratio with PbI2 (molar mass = 461.01 g/mol) we compute the mass of PbI2 precipitate as shown below:
[tex]m_{PbI_2}=0.157molNaI*\frac{1molPbI_2}{2molNaI}*\frac{461.01 gPbI_2}{1molPbI_2} \\\\m_{PbI_2}=36.2gPbI_2[/tex]
Best regards!
According to the equation, 2Al(s) + 6H2O(l) + 2KOH(aq) to make 2K[Al(OH)4](aq) + 3H2(g). How many grams of hydrogen gas would be formed in the reaction of 1.15 grams of Al and excess KOH?
Answer:
0.06457g of H₂
Explanation:
2Al(s) + 6H₂O(l) + 2KOH(aq) → 2K[Al(OH)₄](aq) + 3H₂(g)
Based on the equation 2 moles of Al produce 3 moles of hydrogen.
First, we need to convert mass of Al to moles and then with the chemical equation find moles and mass of hydrogen:
Moles Al (Molar mass: 26.982g/mol):
1.15g Al * (1mol / 26.982g) = 0.04262 moles Al
Moles H₂:
0.04262 moles Al * (3 moles H₂ / 2 mol Al) = 0.06393 moles H₂
Mass hydrogen (Molar mass: 1.01g/mol):
0.06393 moles H₂ * (1.01g/mol) =
0.06457g of H₂What was the molecular geometry for SC16?
Answer:
I'm assuming this is for the SCl₆ compound and not SC₁₆? If so, the molecular geometry is octahedral.
Explanation:
There are 6 regions and zero lone pairs surrounding the central atom (S).
The air particles in the jar become smaller.
List five acids and five bases we come across in our day to day activities under the correct heading.
acids -
citric acid- citrus fruits
lactic acid -milk
amino acids- protein
tannic acid -tea
malic acid -apple
Bases-
baking soda (Nahco3)
Maya adds six grams of sugar to water bottle containing 14 g of warm water what is the total weight of the sugar and water
Answer:
20g
Explanation:
14g+6g=20g
In this lab, you will do experiments to identify types of changes. Using the question format you learned (shown above), write an investigative question that you can answer by doing these experiments. Lab question: How can you distinguish a physical change from a chemical change?
Answer:
a physical change does not change the composition (what it's made of) as a chemical change would.
Physical changes are differentiated from the chemical changes by means of the state of the substance which is obtained after the change.
What are physical changes ?Physical changes are defined as changes which affect only the form of a substance but not it's chemical composition. They are used to separate mixtures in to chemical components but cannot be used to separate compounds to simpler compounds.
Physical changes are always reversible using physical means and involve a change in the physical properties.Examples of physical changes include melting,boiling , change in texture, size,color,volume and density.Magnetism, crystallization, formation of alloys are all reversible and hence physical changes.
They involve only rearrangement of atoms and are often characterized to be changes which are reversible.
Learn more about physical changes,here:
https://brainly.com/question/17931044
#SPJ2
Which term describes the process of water moving from plant leaves to the atmosphere? Air pressure Humidity Transpiration Density
Explanation:
transpiration good luck
Answer:
Transpiration
Explanation:
I took a quiz on the water cycle and this was the correct answer. if I am wrong then I am sorry but I'm pretty sure this is correct.
If the pressure exerted by a gas at 25 degrees C in a volume of 0.044 L is 3.81 atm, how
many moles of gas are present?
Answer:
0.0069 mol
Explanation:
Given data:
Temperature = 25°C
Volume of gas = 0.044 L
Pressure of gas = 3.81 atm
Number of moles of gas = ?
Solution:
The given problem will be solve by using general gas equation,
PV = nRT
P= Pressure
V = volume
n = number of moles
R = general gas constant = 0.0821 atm.L/ mol.K
T = temperature in kelvin
Now we will convert the temperature.
25+273 = 298 K
3.81 atm × 0.044 L = n × 0.0821 atm.L/ mol.K × 298 K
0.17 atm.L = n ×24.47 atm.L/ mol
n = 0.17 atm.L/24.47 atm.L/ mol
n = 0.0069 mol
The moles of gas has a pressure of 3.81 atm and volume 0.044 L has been 6.85 mmol.
The gas has been exhibiting the ideal nature. According to the ideal gas equation:
PV =nRT
P = pressure = 3.81 atm
V = volume = 0.044 L
R = constant = 0.0821
T = temperature = 25 [tex]\rm ^\circ C[/tex] = 298 K
Substituting the value:
3.81 [tex]\times[/tex] 0.044 = n [tex]\times[/tex] 0.0821 [tex]\times[/tex] 298
0.16764 = 24.4658 n
n = 0.00685 mol
n = 6.85 mmol
The moles of gas has a pressure of 3.81 atm and volume 0.044 L has been 6.85 mmol.
For more information about the pressure of a gas, refer to the link:
https://brainly.com/question/17254541