Explanation:
4.5×6.022×10²³
27.099×10²³
According to Avogadro's number, there are 27.10×10²³ atoms in 4.5 moles of Al.
What is Avogadro's number?Avogadro's number is defined as a proportionality factor which relates number of constituent particles with the amount of substance which is present in the sample.
It has a SI unit of reciprocal mole whose numeric value is expressed in reciprocal mole which is a dimensionless number and is called as Avogadro's constant.It relates the volume of a substance with it's average volume occupied by one of it's particles .
According to the definitions, Avogadro's number depend on determined value of mass of one atom of those elements.It bridges the gap between macroscopic and microscopic world by relating amount of substance with number of particles.
Number of atoms can be calculated using Avogadro's number as follows: mass/molar mass×Avogadro's number.As 1 mole =6.023×10²³ atoms , thus,4.5 moles =4.5×6.023×10²³ = 27.10×10²³ atoms.
Thus, there are 27.10×10²³ atoms in 4.5 moles of Al.
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2). A student collects 425 L of oxygen at a temperature of 24.0°C and a pressure
of 0.899 atm. How many moles of oxygen did the student collect?
Answer:
15.5 moles
Explanation:
Applying,
PV = nRT.................. Equation 1
Where P = pressure, V = Volume, n = number of mole, R = molar gas constant, T = Temperature.
Make n the subject of the equation
n = PV/RT............... Equation 2
From the question,
Given: P = 0.899 atm, V = 425 L, T = 24 °C = (273+24) K = 297 K.
Constant: R = 0.083 L.atm/K.mol
Substitute these values into equation 2
n = (0.899×425)/(297×0.083)
n = 15.5 moles
What is the frequency of a wave that has a wavelength of 0.50 m and a speed of 380 m/s?
Answer: f = 760 Hz
Explanation: speed = frequency · wavelength v = fλ.
frequency f = v/ λ = 380 m/s / 0.50 m = 760 Hz
A jar is filled to the top with water, and a piece of cardboard is slid over the opening so that there is only water in the . If the jar is now turned over, will the cardboard fall off? What will happen if there is any air in the jar?
Answer:
it will all fall unless these is air
Explanation:
Answer:
If you do it carefully enough, a small amount of water will pour out of the glass — that's supposed to happen. But try not to let any air bubbles get into the glass. Finally, slowly remove the hand holding the cardboard in place.
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(11) Deduce the number of dyes in food colouring H.
(iii) Suggest why food colouring F does not move during the experiment.
(iv) Explain which two food colourings contain the dye that is likely to be the most soluble the solvent.
(b) Determine which food colouring contains a dye with R, value closest to 0.67
Show your working.
Answer:
(ii) 1 dye
(iii) Food coloring F is insoluble in the solvent
(iv) 'E' and 'H'
(b) Food colouring G
Explanation:
Paper chromatography principle is based on the rates of migration of chemicals across a sheet of paper which are different and it consists of a stationary phase such as the water in the paper and a mobile phase such as the solvent resulting in the partitioning of the components of the mixture across the paper
The solution components are positioned to start in one place from where they migrate and separate out on the chromatography paper
(ii) The number of components into which the food colouring 'H' separates into = 1
Therefore, the number of dyes in food colouring 'H' = 1 dye
(iii) Food coloring 'F' does not move because it is insoluble in the solvent, which is the mobile phase
(iv) The food colouring that contains the dye that is likely to be most soluble in the solvent are does for which the dyes travel furthest, which are;
Food coloring 'E' and 'H'
(b) Using a similar question solution found on 'tutor my self' website, we have;
The [tex]R_f[/tex] values are given as follows;
[tex]R_f = \dfrac{Distance \ moved \ by \ dye}{Distance \ moved \ by \ solvent}[/tex]
The distance moved by the solvent = 5 units
The distance moved by dyes in food colouring 'E' and 'H' = 4 units
The distance moved by dye in food colouring 'G' = 3.3 units
The distance moved by the second dye in food colouring 'E' = 2.7 units
By inspection, we get;
[tex]R_f[/tex] dye in food colouring 'G' = 3.3/5 = 0.66,
Therefore, the dye with [tex]R_f[/tex] value closest to 0.67 is the dye in food colouring 'G'.
Meera added blue copper sulphate crystals to some water in a beaker.
The copper sulphate dissolved in the water.
1 give one way meera could see that the copper sulphate had dissolved in the
Answer:
The solid crystals disappeared
Explanation:
When a soluble solid solute is added to water, the solid solute disappears after a little while. The disappearance of this solute indicates that the solute has been dissolved in water.
In this case, blue copper sulphate crystals are added to water, the blue crystals disappear leaving only a blue solution. The disappearance of these blue copper sulphate crystals indicates that the substance has dissolved in water.
What volume of water is needed to make 5.41 M solution with 47.71 moles of HCL?
Answer:
0.113 liters
Explanation:
5.41 M / 47.71 moles = 0.113 liters
why do we need to rinse the mouth before collecting the saliva
When carbon disulfide, CS2, forms from its elements. Heat is absorbed. How much heat would be required to produce 5.0 moles of carbon disulfide
Answer:
5.9 × 10² kJ
Explanation:
When carbon disulfide, CS₂, forms from its elements, heat is absorbed. The corresponding value for the standard enthalpy of formation of carbon disulfide is 117.36 kJ/mol. The thermochemical equation that represents this process is:
C(graphite) + 2 S(s, rhombic) ⇒ CS₂(g) ΔH°f = 117.36 kJ/mol
117.36 kJ of heat are absorbed when 1 mole of CS₂ is formed. The amount of heat absorbed when 5.0 moles of CS₂ are formed is:
5.0 mol × 117.36 kJ/mol = 5.9 × 10² kJ
5). At what temperature (K) will 0.854 moles of neon gas occupy 12.3 L at 1.95
atmospheres?
Answer:
338.38 K
Explanation:
Applying,
PV = nRT............... Equation 1
Where P = pressure, V = Volume, R = Temperature, n = number of moles, T = temperature.
Make T the subject of the equation,
T = PV/nR............. Equation 2
From the question,
Given: P = 1.95 atm, V = 12.3 L, n = 0.854 moles
Constant: R = 0.083 L.atm/K.mol
Substitute these values into equation 2
T = (1.95×12.3)/(0.854×0.083)
T = 338.38 K
How would you find the density of a can of soda pop?
A. Find the mass of the can of soda pop and then multiply by the number of cubic centimeters in the can
B. Find the mass of the can of soda pop and then divide by the number of cubic centimeters in the can
C. Convert a gallon into cubic centimeters and then divide by the mass of the can of soda pop
D. Convert a gallon into cubic centimeters and then subtract the mass of the can of soda pop
Answer:
it's A.
Explanation:
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what does the period number on the periodic table tell us?
Answer:
The period number on the Periodic table tells you the total number of orbits that the atom will have. In other words, the period number indicates the number of energy levels (or energy orbit) of an atom. For example, 1st period indicates that these elements possess 1 energy shell (or energy orbit).
Explanation:
A chemist observed bubbling and fizzing after adding an acid solution to a
white powdery substance in a beaker. Which of the following can be
inferred?
Answer:
a chemical reaction occured
Explanation:
bubbling and fizzing after adding a substance, most offten means a chemical reaction is happening
How many moles of aluminum are in 54 grams
Find the hydroxide concentration of a LiOH soultion that has a pOH of 8.65.
[OH] = _____ (round to 2 decimal places)
Answer: i need help
Explanation:
2. Identify the limiting reactant when 4.68 g of iron reacts with 2.88 g of sulfur to produce Fes.
Fe +
_Sg → FeS
B
C с
A
+
Help please I’ll mark brainliest
Answer:
Iron is limiting reactant
Explanation:
Based on the reaction:
Fe + S → FeS
1 mole of iron reacts per mole of Sulfur
To solve this question we must convert the mass of each reactant to moles using molar masses of each reactant. As the reaction is 1:1, the reactant with the lower amount of moles is limiting reactant.
Moles Fe -Molar mass: 55.845g/mol-
4.68g * (1mol / 55.845g) = 0.0838 moles
Moles S -Molar mass: 32.065g/mol-
2.88g * (1mol / 32.065g) = 0.0898 moles
As the amount of moles of Fe < Moles S,
Iron is limiting reactant
When 4.68 g of iron reacts with 2.88 g of sulfur to produce FeS, iron is the limiting reagent.
What is limiting reagent?
If in a chemical reaction two reactants are present and one of them is present in less quantity as compared to other, is known as limiting reagent.
Given chemical reaction is:
Fe + S → FeS
From the stoichiometry of the reaction it is clear that equal moles of both reactant is required for the formation of product, so their mole ratio is 1:1.
Now we calculate the moles by using the formula:
n = W/M, where
W = given mass
M = molar mass
Moles of 4.68g of iron = 4.68g / 55.845g/mole = 0.0838 moles
Moles of 2.88 of sulfur = 2.88g / 32.065g/mole = 0.0898 moles
Moles of iron is less as compare to the sulfur, so it is the limiting reagent.
Hence, iron is the limiting reagent.
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You are given 250 mL of a 12.0 M solution of KNO3. To obtain a 5.0 M, to what volume does the solution need to be diluted to?
600 ml
104.17 mL
0.24 mL
60 mL
Answer:
600 mL
Explanation:
molarity 1 * volume 1 = molarity 2 * volume 2. So this means 12 * 250 = 3000 and divide that by 5 to get 600 mL.
Potassium hydroxide is partially soluble as shown by the
following reaction:
KOH(s) K+ (aq) + OH(aq)
What is the poH of a 3.32 x 10-5 M KOH solution?
pOH =
Your answer should be rounded to three significant figures. Do not Include
units in your answer.
Answer: 4.48 or 4.47
Which element, when combined with Fluorine, would form an COVALENT compound?
A.Lithium
B.Iron
C.Phosphorus
D.Sodium
Answer:
Explanation:
A covalent compound is a compound formed by covalent bonds. A covalent bond is formed between two atoms where electrons are shared between the two atoms. This forms a molecule.
What determines whether two elements will form a covalent compound or not is the number of valence electrons present in each of the elements.
Fluorine will form a covalent compound with phosphorous because fluorine has 5 electrons in its outermost shell. It needs 3 more to become stable.
Phosphorous also has 5 valence electrons. It needs 3 more to become stable.
What happens is that 3 atoms of FLuorine combine with one atom of Phosphorus, sharing the valence electrons between themselves. This leads to the formation of the PF3 molecule.
Both the Phosphorous and the Fluorine are now stable.
Answer: Phosphorus
Explanation: since both are non-metals they would both create a covalent bond.
Use the given Nernst equation and reaction to solve this problem. What is the potential of this cell with the given conditions?
2Li (aq) + F2(g) 2Li+(aq) + 2F- (aq)
E° = +5.92 volts
T = 200°C
[Li+] = 10.0 molar
[F-] = 10.0 molar
Answer:
The 2nd one is the one
Explanation:
and it isn't writen out all the way
(part 1 of 3) Copper reacts with silver nitrate through a single replacement. If 1.29 g of silver are produced from the reaction, how much copper(II) nitrate is also produced? Answer in units of mol. (part 2 of 3) How much Cu is required in this reaction? Answer in units of mol. (part 3 of 3) 1.0 points How much AgNO3 is required in this reaction? Answer in units of mol.
Answer:
See explanation.
Explanation:
Hello there!
In this case, according to the described chemical reaction, we first write the corresponding equation to obtain:
[tex]Cu+2AgNO_3\rightarrow 2Ag+Cu(NO_3)_2[/tex]
Thus, we proceed as follows:
Part 1 of 3: here, since the molar mass of silver and copper (II) nitrate are 107.87 and 187.55 g/mol respectively, and the mole ratio of the former to the latter is 2:1, we can set up the following stoichiometric expression:
[tex]m_{Cu(NO_3)_2}=1.29gAg*\frac{1molAg}{107.87gAg}*\frac{1molCu(NO_3)_2}{2molAg}*\frac{187.55gCu(NO_3)_2}{1molCu(NO_3)_2} \\\\m_{Cu(NO_3)_2}=1.12gCu(NO_3)_2[/tex]
Part 2 of 3: here, the molar mass of copper is 63.55 g/mol and the mole ratio of silver to copper is 2:1, the mass of the former that was used to start the reaction was:
[tex]m_{Cu}=1.29gAg*\frac{1molAg}{107.87gAg}*\frac{1molCu}{2molAg}*\frac{63.55gCu)_2}{1molCu} \\\\m_{Cu}=0.380gCu[/tex]
Part 3 of 3: here, the molar mass of silver nitrate is 169.87 g/mol and their mole ratio 2:2, thus, the mass of initial silver nitrate is:
[tex]m_{AgNO_3}=1.29gAg*\frac{1molAg}{107.87gAg}*\frac{2molAgNO_3}{2molAg}*\frac{169.87gAgNO_3}{1molAgNO_3} \\\\m_{AgNO_3}=2.03gAgNO_3[/tex]
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What are the two limitations of earth plates
Answer:
The tectonic style and viability of modern plate tectonics in the early Earth is still debated. Field observations and theoretical arguments both in favor and against the uniformitarian view of plate tectonics back until the Archean continue to accumulate. Here, we present the first numerical modeling results that address for a hotter Earth the viability of subduction, one of the main requirements for plate tectonics. A hotter mantle has mainly two effects: 1) viscosity is lower, and 2) more melt is produced, which in a plate tectonic setting will lead to a thicker oceanic crust and harzburgite layer. Although compositional buoyancy resulting from these thick crust and harzburgite might be a serious limitation for subduction initiation, our modeling results show that eclogitization significantly relaxes this limitation for a developed, ongoing subduction process. Furthermore, the lower viscosity leads to more frequent slab breakoff, and sometimes to crustal separation from the mantle lithosphere. Unlike earlier propositions, not compositional buoyancy considerations, but this lithospheric weakness could be the principle limitation to the viability of plate tectonics in a hotter Earth. These results suggest a new explanation for the absence of ultrahigh-pressure metamorphism (UHPM) and blueschists in most of the Precambrian: early slabs were not too buoyant, but too weak to provide a mechanism for UHPM and exhumation.
Explanation:
When writing the formulas for a compound that contains a polyatomic ion, ... ?
Answer:
The cation is written first in the name; the anion is written second in the name. Rule 2. When the formula unit contains two or more of the same polyatomic ion, that ion is written in parentheses with the subscript written outside the parentheses.
When writing the formula of a compound that contains polyatomic ion, the metal is written first followed by the central atom in the ion and then other atoms that surround the central atom.
A poly atomic ion refers to an ion that comprises of more than one atom. Such ions are common in chemistry. Examples of polyatomic ions include; PO4^3-, BH4^- etc.
When writing the formula of a compound that contains a polyatomic ion, the metal is written first then the central atom in the ion follows before other atoms that surround the central atom in the ion.
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