Answer:
125 g
Explanation:
The following data were obtained from the question:
Half-life (t½) = 5.3 years.
Original amount (N₀) = 1000 g
Time (t) = 15.9 years.
Amount remaining (N) =?
Next, we shall determine the number of half-lives that has elapsed. This can be obtained as follow:
Half-life (t½) = 5.3 years.
Time (t) = 15.9 years.
Number of half-lives (n) =?
n = t / t½
n = 15.9 / 5.3
n = 3
Thus, 3 half-lives has elapsed.
Finally, we shall determine the amount of Co–60 that is remaining. This can be obtained as follow:
Original amount (N₀) = 1000 g
Number of half-lives (n) = 3
Amount remaining (N) =?
N = 1/2ⁿ × N₀
N = 1/2³ × 1000
N = 1/8 × 1000
N = 0.125 × 1000
N = 125 g
Therefore, the amount of Co–60 that is remaining is 125 g
If 2.45 g of iron are placed in 1,5 L of 0.25M HCl, how many grams of FeCl2 are obtained? Identify the limiting and excess reactants in this single replacement reaction. Fe + 2HCl = FeCl2 + H2
Answer:
[tex]m_{FeCl_2}=0.652gFeCl_2[/tex]
Explanation:
Hello there!
In this case, according to the given information and the chemical reaction, whereby iron and hydrochloric acid react in a 1:2 mole ratio, it is firstly necessary to calculate the moles of iron (II) chloride from each reactant in order to figure out the limiting reactant:
[tex]n_{FeCl_2}=2.45gFe*\frac{1molFe}{55.845gFe}*\frac{1molFeCl_2}{1molFe}=0.0439molFeCl_2\\\\ n_{FeCl_2}=1.5L*0.25\frac{molHCl}{L} *\frac{1molHCl}{36.46gHCl}*\frac{1molFeCl_2}{2molHCl}=0.00514molFeCl_2[/tex]
In such a way, we infer the maximum moles of FeCl2 product are yielded by HCl, for which it is the limiting reactant. Finally, we calculate the grams of product by using its molar mass as shown below:
[tex]m_{FeCl_2}=0.00514molFeCl_2*\frac{126.75gFeCl_2}{1molFeCl_2} \\\\m_{FeCl_2}=0.652gFeCl_2[/tex]
Regards!
Which of the following is an example of potential energy?
A. The energy of moving particles
B. The energy in chemical bonds
C. The energy of vibrating air
D. The energy of a runner on a flat road
Answer:
B
Explanation:
Chemical bonds are a form of potential energy.
Why do we need cells to divide? Give two examples.
Answer:
Cells need to divide to reproduce.
Explanation:
They go through numerous stages, such as mitosis to further replicate themselves. They can't get things done alone, so they have to work in numbers.
A 1 liter solution contains 0.383 M hydrofluoric acid and 0.510 M potassium fluoride.
Addition of 0.096 moles of calcium hydroxide will:
(Assume that the volume does not change upon the addition of calcium hydroxide.)
Raise the pH slightly
Lower the pH slightly
Raise the pH by several units
Lower the pH by several units
Not change the pH
Exceed the buffer capacity
Answer:
Lower the pH slightly
Explanation:
The mixture of HF, hydrofluoric acid and KF, potassium fluoride produce a buffer that is defined for the equilibrium:
HF(aq) → H⁺(aq) + F⁻(aq)
The buffer can maintain the pH of a solution despite the addition of strong bases or acids.
The reaction of HF with Ca(OH)2 is:
2HF + Ca(OH)2 → 2H2O + CaF2
That means the calcium hydroxide is decreasing the concentration of HF. Based on the equilibrium, the H+ and F- ions will decrease in order to produce more HF. As H+ is decreasing due the equilibrium and not for the addition of a strong base, the pH is decreasing slightly.
1. How many grams of water are in a cup containing
0.1 moles of H2O?
Answer:
Explanation:
fdcdf
A sample of aluminum requires 341 J of energy to raise the temperature from 18.0ºC to 55.0ºC. Calculate the mass of the aluminum sample.
Answer:
10.22g
Explanation:
Using the formula as follows:
Q = m × c × ∆T
Where;
Q = amount of heat required (J)
m = mass of substance (g)
c = specific heat of substance (J/g°C)
∆T = change in temperature (°C)
According to the information given in this question;
Q = 341J
m = ?
∆T = 55.0ºC - 18.0ºC = 37°C
c of aluminum = 0.902J/g°C
Using Q = m × c × ∆T
341 = m × 0.902 × 37
341 = 33.374m
m = 341 ÷ 33.374
m = 10.22g
How many moles of sodium hydroxide would have to be added to 150 mL of a 0.483 M acetic acid solution, in order to prepare a buffer with a pH of 4.480
Answer:
0.068 moles of sodium hydroxide would have to be added to 150 mL of a 0.483 M acetic acid solution
Explanation:
As we know
pH = pKa + log [salt]/[acid]
4.480= 4.74 + log [salt]/[acid]
log [salt]/[]acid] = -0.06
[salt]/[acid] = 0.87
moles acid = 0.150 L x 0.483 mol/L = 0.07245 moles acid
x/0.07245-x = 0.87
X- 0.07245 X = 0.87 *0.07245
X = 0.068 moles
Which force is most responsible for binding together an atom’s protons and neutrons?
electrostatic
gravitational
nuclear
magnetic
gravitational force is most responsible for binding together an atom’s protons and neutrons.
What is gravitational force?In physics, gravity (from Latin gravitas 'weight') is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is by far the weakest of the four fundamental interactions, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a result, it has no significant influence at the level of subatomic particles. However, gravity is the most significant interaction between objects at the macroscopic scale, and it determines the motion of planets, stars, galaxies, and even light.
On Earth, gravity gives weight to physical objects, and the Moon's gravity causes tides in the oceans. Gravity also has many important biological functions, helping to guide the growth of plants through the process of gravitropism and influencing the circulation of fluids in multicellular organisms. Investigation into the effects of weightlessness has shown that gravity may play a role in immune system function and cell differentiation within the human body.
The gravitational attraction between the original gaseous matter in the Universe allowed it to coalesce and form stars which eventually condensed into galaxies, so gravity is responsible for many of the large-scale structures in the Universe. Gravity has an infinite range, although its effects become weaker as objects get farther away.
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Mercury: Mineral or Not Mineral? Mineral Not Mineral
Answer:
not a mineral but is a “mineraloid
Explanation:
not mineral
Explanation: its an element but it is not a mineral
Suppose the available nutrients in the soil of an ecosystem decrease. Over time, which adaptation is MOST LIKELY to evolve among the plants that survive there?
Answer:
Root system will become larger or extend farther
Explanation:
If nutrient in soil decrease, the plant's roots system will likely become larger and extend out deeper and farther to get all the nutrients it possibly can
15. Objects can have kinetic energy, potential energy, or both. Energy can be in the form of motion. Energy can
also be stored by objects in various ways, including position, chemical bonds, or physical state.
Which statement is true? And why?
a. An object’s mass has no effect on its potential energy.
b. Potential energy is converted to kinetic energy as a stationary object begins to move.
c. Kinetic energy is converted to potential energy as a stationary object begins to move.
d. A stretched rubber band stores no energy.
Answer: b because Potential energy is converted to kinetic energy as a stationary object begins to move.
Explanation:
The materials or compounds that are changed into new compounds in a chemical reaction are known as ?
Answer:
The starting substances of a chemical reaction are called the reactants, and the new substances that result are called the products.
A student determines that the theoretical yield of CaCO3, from a precipitation reaction is 21.5 grams
However, this student only recovers 19.9 grams of precipitate through filtration of the solution.
What would be this student's percent yield?
A. 92.6%
B. 0.93%
C. 108%
D. 85.6%
Answer:
92.6
Explanation:
How many electrons are in the highest occupied energy level of a neutral chlorine atom?
Magnesium hydroxide and sodium hydroxide are both strong bases. The pH of a saturated solution of sodium hydroxide is greater than 14. The pH of a saturated
solution of magnesium hydroxide is about 10.2. Why do the solutions have different pH values?
Answer: Solubility of NaOH is greater and there are more OH- ions in solution.
Explanation: Reactions : NaOH (s) ⇒ Na+ (aq) + OH- (aq)
Mg(OH)2 (s) ⇒ Mg2+ (aq) + 2 OH-(aq)
Although in same amount of moles, Mg(OH)2 produces
two (OH-)-ions in water solution, solubility of Mq(OH)2 is smaller.
Concentration [OH-]ions is smaller in saturated water solution
of Mg(OH)2
What cell structure is best represented by the image?
A.
a non-permeable cell wall
B.
a selectively permeable membrane
C.
a waterproof nuclear envelope
D.
a permeable exoskeleton
Answer:where is the image
Explanation:
Answer:
B.
a selectively permeable membrane
Explanation:
What number should be written in front of Na to balance the equation?
Na + MgCl2 → NaCl + Mg
1
2
3
4
In order to balance the chemical equation, the coefficient of Na should be 2.
Solid mercury(II) oxide decomposes into liquid mercury and oxygen gas upon the absorption of 90.8 kJ for each mole of mercury(II) oxide decomposed.
The question is incomplete, the complete question is;
Solid mercury (II) oxide decomposes into liquid mercury and oxygen gas upon the absorption of 90.8 kJ for each mole of mercury (II) oxide decomposed.
What is the reaction without the energy?
What is the appropriate side of the equation and value for the energy term?
Answer:
See Explanation
Explanation:
The equation of the reaction is;
2HgO(s) ==> 2Hg(l) + O2(g)
Let us recall that a chemical equation is balanced if the number of atoms of each element on both sides of the reaction equation are the same. There are two atoms each of mercury and oxygen on both sides of the reaction equation hence the equation is balanced.
In order to write a thermochemical equation, the heat of reaction is written on the right hand side of the reaction equation after writing the products as follows;
2HgO(s) ==> 2Hg(l) + O2(g) ΔH = +90.8 kJ
Food Science is the study of the physical, biological, and chemical makeup of food; the
causes of food deterioration; and the concepts ulderlying food processing.
True
False
which formulas could represent the empirical formula and the molecular formula of a given compound?
A. CH2O, C4H6O4
B. CHO, C6H12O6
C. CH4, C5H12
D. CH2, C3H6
Answer:
d
Explanation:
d
The formulas which could represent the empirical formula and the molecular formula of a given compound are CH₂, C₃H₆ as the smallest possible is 2 which on multiplying the subscripts of empirical formula give molecular formula.
What is empirical formula?Empirical formula of a compound is defined as the simplest whole number ratio of atoms which are present in a compound.It does not make any mention of the arrangement of atoms or the number of atoms. The empirical formula gives information about the ratio of number of atoms which are present in a compound.
Molecular formula is determined from the empirical formula by dividing the molar mass of a compound by the empirical formula mass. The resultant which should be a whole number or very close to the whole number , then the subscripts are multiplied by the whole number to get the molecular formula.
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Write and balance the equation for the neutralization reaction between phosphoric acid and
sodium hydroxide.
Answer: H3PO4(aq)+3NaOH(aq)→Na3PO4(aq)+3H2O(l)
Explanation:
What type of bond would form between atoms of the
following elements:
Calcium (Ca) and Oxygen (O)?
Octane (C8H18) is found in gasoline. It is burned for fuel in a combustion
reaction. The unbalanced combustion reaction for octane is shown below.
C8h18+ O2 → C02 + H2O + heat
When the reaction is balanced, how many carbon dioxide molecules are
produced for every octane molecule burned?
Answer:
Explanation:
It's 8
atomic weight of first 30 element in periodic table
Answer:
The answer is in the explanation
Explanation:
The atomic weight of an element is defined as the mass of 1 mole of atoms of the element. To find the atomic weight of the first 30 elements we must see our periodic table:
# Element Atomic Weight
1 Hydrogen 1.008
2 Helium 4.0026
3 Lithium 6.94
4 Beryllium 9.0122
5 Boron 10.81
6 Carbon 12.011
7 Nitrogen 14.007
8 Oxygen 15.999
9 Fluorine 18.998
10 Neon 20.180
11 Sodium 22.990
12 Magnesium 24.305
13 Aluminium 26.982
14 Silicon 28.085
15 Phosphorus 30.974
16 Sulfur 32.06
17 Chlorine 35.45
18 Argon 39.948
19 Potassium 39.098
20 Calcium 40.078
21 Scandium 44.956
22 Titanium 47.867
23 Vanadium 50.942
24 Chromium 51.996
25 Manganese 54.938
26 Iron 55.845
27 Cobalt 58.933
28 Nickel 58.693
29 Copper 63.546
30 Zinc 65.38
What do greenhouse gases do on Earth?
Answer:
It holds heat from the sun close to Earth.
Explanation:
Hope this helps and have a great day. :)
Isoniazid is used in the treatment of tuberculosis and multiple sclerosis. Identify each lone pair as either localized or delocalized. Justify your answer in each case.
Answer:
Please find the complete question and its solution in the attached file:
Explanation:
1.. A saturatedsolutionA.contains more solute thansolvent.B.contains more solvent thansolute.C.contains equal moles of solute andsolvent.D.contains the maximum amount of solute that will dissolve in that solvent at that temperature.E.contains a solvent with only sigma bonds and no pi bonds (i.e. only single bonds, with no doubleor triplebonds).
Answer:
D. contains the maximum amount of solute that will dissolve in that solvent at that temperature.
Explanation:
Solubility is a term used to describe how readily a substance can be dissolved in a solvent to form a solution. Thus, a substance is said to be soluble if it dissolves completely in a solvent and insoluble if it doesn't dissolve or only dissolves partially.
For example, sodium chloride (NaCl) when mixed with water dissociates into sodium and chloride ions. Thus, salt (sodium chloride) is said to be soluble because it dissolves completely in water.
Hence, a compound that dissolves in water to produce an aqueous solution is said to be soluble in water. Also, the solute of an aqueous solution that conducts electricity is called an electrolyte.
In Chemistry, dissolution can be defined as the process of dissolving or dissociating a solute in solid, liquid or gaseous phase into fragmented particles by a solvent in order to form a solution. For dissolution to occur in solids, the crystalline structure of the substance must be broken up so as to release ions, atoms or molecules to produce a solution. For liquid and gases, the substance to be dissolved must form a non-covalent bond with the solvent to produce a solution.
Generally, a saturated solution contains the maximum amount of solute that will dissolve in that solvent at that temperature.
How much potassium chloride is needed to make 0.500 m solution with 1.50 L of water?
Answer:
55.9 g KCl.
Explanation:
Hello there!
In this case, according to the definition of molality for the 0.500-molar solution, we need to divide the moles of solute (potassium chloride) over the kilograms of solvent as shown below:
[tex]m=\frac{mol}{kilograms}[/tex]
Thus, solving for the moles of solute, we obtain:
[tex]mol=m*kilograms[/tex]
Since the density of water is 1 kg/L, we obtain the following moles:
[tex]mol=0.500mol/kg*1.50kg\\\\mol=0.75mol[/tex]
Next, since the molar mass of KCl is 74.5513 g/mol, the mass would be:
[tex]0.75mol*\frac{74.5513g}{1mol}\\\\55.9g \ KCl[/tex]
Regards!
Given 23 g of potassium nitrate per 25 g of water, what temperature should create a saturated solution?
Answer:
At about 51 °C
Explanation:
Hello there!
In this case, according to the attached solubility chart of potassium nitrate, our first step for this problem is to calculate the grams of this solute in 100 g given that 23 g are soluble in 25 g of water:
[tex]\frac{23g}{25g}=\frac{x}{100g}\\\\x= \frac{23g*100g}{25g}=92g[/tex]
Thus, such solubility of 92 g in 100 g of water is exhibited at about 51 °C.
Regards!
Find the mass of copper that was
heated from 32°C to 130°C by using
5400 joules of heat. Cou=.385 J/goC
Answer:
143.12 g
Explanation:
From the question given above, the following data were obtained:
Initial temperature (T₁) = 32 °C
Final temperature (T₂) = 130 °C
Heat (Q) = 5400 J
Specific heat capacity (C) = 0.385 J/gºC
Mass (M) =?
Next, we shall determine the change in temperature of copper. This can be obtained as follow:
Initial temperature (T₁) = 32 °C
Final temperature (T₂) = 130 °C
Change in temperature (ΔT) =?
ΔT = T₂ – T₁
ΔT = 130 – 32
ΔT = 98 °C
Finally, we shall determine the mass of copper. This can be obtained as follow:
Change in temperature (ΔT) = 98 °C
Heat (Q) = 5400 J
Specific heat capacity (C) = 0.385 J/gºC
Mass (M) =?
Q = MCΔT
5400 = M × 0.385 × 98
5400 = M × 37.73
Divide both side by 37.73
M = 5400 / 37.73
M = 143.12 g
Therefore, the mass of copper is 143.12 g