Answer:
1 g
Explanation:
The following data were obtained from the question:
Original amount (N₀) = 32 g
Time (t) = 71.5 days
Half-life of phosphorus (t½) = 14.3 days
Amount remaining (N) =?
Next, we shall determine the rate of disintegration. This can be obtained as follow:
Half-life of phosphorus (t½) = 14.3 days
Decay constant (K) =?
K = 0.693 / t½
K = 0.693 / 14.3
K = 0.0485 /day
Finally, we shall determine the amount remaining as illustrated below:
Original amount (N₀) = 32 g
Time (t) = 71.5 days
Decay constant (K) = 0.0485 /day
Amount remaining (N) =?
Log (N₀/N) = Kt/2.303
Log (32/N) = 0.0485 × 71.5 / 2.303
Log (32/N) = 3.46775 / 2.303
Log (32/N) = 1.5058
Take the antilog of 1.5058
32/N = antilog (1.5058)
32/N = 32.05
Cross multiply
32 = N × 32.05
Divide both side by 32.05
N = 32 / 32.05
N = 0.998 ≈ 1 g
Thus, the amount remaining after 71.5 days is approximately 1 g.
The half-life of a radioactive substance refers to the time taken for the substance to Decay to half of its initial size. Hence, the mass of the substance left after 71.5 days is 1 gram.
Initial mass = 32 g Half life = 14.3 daysAfter 14.3 days ;
32 / 2 = 16 gramsAfter 14.3 × 2 = 28.6 days :
16/2 = 8 gramsAfter 14.3 × 3 days = 42.9 days :
8 / 2 = 4 gramsAfter 14.3 × 4 days = 57.2 days :
4 /2 = 2 gramsAfter 14.3 × 5 days = 71.5 days :
2 /2 = 1 gram.Hence, the mass of the sample left after 71.5 days would be 1 gram.
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When 2.5 moles of N2 react according to the reaction below, how many moles of NH3 will be produced?
N2 + 3 H2 --> 2 NH3
O 2.5 moles NH3
0 2.0 moles NH3
O 1.3 moles NH3
5.0 moles NH3
Answer:
5 mol
Explanation:
by stoichiometry
nN2/1=nNH3/2
2.5=nNH3/2
nNH3=2.5×2
nNH3= 5 mol
Answer: I got 5.0 moles
Explanation:
write the complete balanced equation for the decomposition of AI(CIO3)3.
Answer:
2AL(ClO3)3 → 2ALCl3 + 9O2
Explanation:
1. Why is soil erosion relatively less in dense forests as compared to barren, open fields?
Because the deep roots of big trees hold the soil and don't let it slip away simply by rain or wind.
Answer:
the roots of the trees keep the soil in place opposed to a barren landscape that has little to no plants to keep the soil in place
hope this helps (╹ڡ╹ )
What is the term
chemistry
Answer:
Chemistry is the scientific study of the structure of substances, how they react when combined and how they behave under different situations.
Answer:
The branch of science that deals with the identification of the substances of which matter is composed; the investigation of their properties and the ways in which they interact, combine, and change; and the use of these processes to form new substances.
Explanation:
Hope this helps!!!!!!
:)
6H2 represents how many atoms of hydrogen?
Answer:
i think its 12, but i'm not 100% sure
Explanation:
Which of the following is an indication of a physical change?
O A. The formation of a new substance
O B. Giving off a smell
O C. A change in the shape of a substance
O D. The production of gas and heat
Answer:
A change in the shape of a substance
Explanation:
Because when ths shape of a sunstance changes , its physical appearance changes .A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.
When 0.25 moles of NH3 are produced according to the reaction below, how many moles of H2 must have reacted?
N2 + 3 H2 --> 2 NH3
O 1.5 moles H2
O 0.38 moles H2
O 0.25 moles H2
O 0.17 moles H2
Answer:
Explanation:
by stoichiometry
nNH3/2=nH2/3
0.25/2=nH2/3
nH2=0.25×3/2
nH2=0.375 mol
so its 0.38 mol
Answer:
I have this quiz rn I will try 0.38 if it is right I’ll edit this and say that
Explanation:
If 150 G of war started burning 300 G of where as was left behind how many grams of CO2 gas is released
Answer:
geruow0irghvn3p0unhie0ghik
Explanation:
Which part of the atom can be transferred from one atom to another to form
ions?
a. Protons
b. Neutrons
c. Valence Electron
d. Nucleus
Answer:
Explanation: Valance Electron
Help me with homework.
The chemical equation is said to be balanced if the number of atoms in the reactants and products is the same
Further explanationEquation balanced ⇒ total number of atoms in reactants(on the left)= total number of atoms in products(on the right)
H₂+O₂---> H₂O
Reactants : H₂, O₂
Products : H₂O
not balanced
H₂O₂ ---> H₂O+O₂
Reactants : H₂O₂
Products : H₂O, O₂
not balanced
Na+O₂ ---> Na₂O
Reactants : Na, O₂
Products : Na₂O
not balanced
N₂+H₂ ---> NH₃
Reactants : N₂, H₂
Products : NH₃
not balanced
P₄+O₂---> P₄O₁₀
Reactants : P₄, O₂
Products : P₄O₁₀
not balanced
Fe+H₂O ----> Fe₃O₄ + H₂
Reactants : Fe, H₂O
Products : Fe₃O₄
not balanced
In lab you reacted 60 grams of propane (C3H8) with 13 grams of oxygen gas (O2). Your
reaction made 63 grams of water (H2O). The reaction is shown below:
How much carbon dioxide (CO2) is released into the air?
C3H8 + 5O2 ------> 3CO2 + 4H2O
10 g
73 g
120 g
1368
Answer:
120g
Explanation:
Based on the reaction, when 1 mole of propane and 5 moles of oxygen react, 3 moles of CO2 and 4 moles of H2O are produced. The ratio of production is 3 moles of CO2 per 4 moles of H2O.
Thus, we need to convert mass of water to moles using its molar mass:
Moles H2O (Molar mass: 18g/mol):
63g H2O * (1mol / 18g) = 3.5 moles H2O
Converting to moles of CO2:
3.5 moles H2O * (3 moles CO2 / 4 moles H2O) = 2.625 moles CO2
Mass CO2 (Molar mass: 44g/mol):
2.625 moles CO2 * (44g / mol) = 115.5g of CO2 are released
120gWhich of the following best describes a hypothesis?
A. An explanation that is supported by scientific data
B. A proven explanation for experimental results
c. A possible answer to a scientific question
D. A question about the natural world
please help i will give brainliest
The density of lead is 11.4g/cm3. What volume, in ft3, would be occupied by 10.0 g of lead?
Answer:
The volume is 3.09 ft^3.
Explanation:
The formula for volume is mass divided by density. 10.0 g / 11.4 g/cm^3 = 0.87719. Converted to cubis foot is 3.09 ft^3. I hope this helps you.
how many sig figs are in 0.0093
Answer:
there are two significant figures
Explanation:
Answer:
there are two
Explanation:
because the zeros dont count
Can someone help? Ill give brainliest!
Directions: count each side of the reaction then Circle yes or no if it follows the law of conservation of mass
Answer:
Explanation:
before the reaction you have K=2 and Cl=4
after the reaction K=2 and Cl=2 so it does not follow the law of conservation
Is vacuole a plant or animals cell
Answer:
plant
Explanation:
let me know if correct
how do i caculate velocity
Answer:
Velocity Equation in these calculations:
Final velocity (v) of an object equals initial velocity (u) of that object plus acceleration (a) of the object times the elapsed time (t) from u to v.
Explanation:
Help please! A gas occupies 500 mL at 270 mm Hg and 55°C. If the pressure is changed to 1.8 atm and the temperature is
increased to 100°C, what is the new volume? Be sure to show the setup and the final answer and unit.
Show Your Work
Answer:
V₂ = 112.14 mL
Explanation:
Given data:
Initial volume = 500 mL
Initial pressure = 270 mmHg (270/760 =0.355 atm)
Initial temperature = 55 °C (55 +273 = 328 K)
Final temperature = 100°C (100+273 = 373 K)
Final volume = ?
Final pressure = 1.8 atm
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 = 0.355 atm × 500mL × 373 K / 328 K × 1.8 atm
V₂ = 66207.5 atm .mL. K / 590.4 K.atm
V₂ = 112.14 mL
Use the model to answer the question.
Which element symbol actually represents the model?
Plz answer
Answer:
B
Explanation:
Boron has 5 protons.
Which of the following subatomic particles are found surrounding the nucleus and have a negative charge?
F negatrons
G neutrons
H protons
J electrons
Answer:
J electrons
Explanation:
Electrons are the negatively charged subatomic particles that surrounds the nucleus of an atom.
Electrons occupy the bulk volume of an atom. These particle was discovered by J.J ThomsonThey found orbiting the extra-nuclear space of every atom. The nucleus is made up of protons and neutrons.An independent variable is....
A: What we measure
B: What we change
C: What stays the same
D: What we conclude
Answer:
B - What we change
Explanation:
Dependent Variable - What we measure
Control Variable - what stays the same
Conclusion - what we conclude
Hope this can Help!
:D
What’s the answer????
Answer:
Greater
Greater
Explanation:
The amplitude of a wave is the height of the wave or the vertical displacement of the wave motion. We determine a wave amplitude usually by looking at the graph of the wave.
Amplitude is directly proportional to the energy of a wave. The higher the amplitude of a wave, the more its energy.
Frequency is the number of waves that passes a point at a particular instance of time. It is also directly proportional to the energy carried by a wave. The higher the frequency of a wave, the greater its energy.
We can change the substance chemically by
freezing it.
True or false
Niels Bohr’s model of the atom helped to explain
Answer:
a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits.
Explanation:
At the Beltway Outlet store, you buy x computer games for 13$ each and a magazine for 4$. Write an expression in simplest form that represents the total amount of money you spend. Someone please help
Answer:
y = 13x + 4
Explanation:
Given parameters:
number of computer games bought = x
cost of each games = $13
number of a magazine = 1
cost of magazine = $4
Unknown:
Total amount of money spent = ?
Solution:
The total amount spent;
let total amount = y
y = total cost of magazine + total cost of computer games
total cost of magazine =$4
total cost of computer games = 13x
y = 13x + 4
How many moles of Cl2 are needed in order to produce 100.0 grams of FeCl3 given the following
equation: 2 Fe + 3 Cl2 → 2 FeCl3
B
T
Answer:
0.92moles
Explanation:
Given reaction:
2Fe + 3Cl₂ → 2FeCl₃
Mass of FeCl₃ = 100g
Unknown:
Number of moles of Cl₂ needed = ?
Solution:
To solve this problem, we work from the known specie to the unknown.
From the mass of the FeCl₃ given, we can solve for the number of moles of the unknown.
Number of moles of FeCl₃;Number of moles = [tex]\frac{mass}{molar mass}[/tex]
Molar mass of FeCl₃ = 56 + 3(35.5) = 162.5g/mol
Number of moles = [tex]\frac{100}{162.5}[/tex] = 0.62mole
From the reaction expression;
2 mole of FeCl₃ is produced from 3 moles of Cl₂
0.62 mole of FeCl₃ will be produced from [tex]\frac{0.62 x 3}{2}[/tex] = 0.92mole
The number of moles of Cl₂ = 0.92moles
Which of the following most likely happens when thermal energy is removed from a chemical reaction?
Answer:
fewer collisions occur between particles or lowering the temperature
Explanation:
Air that has been removed from a bell jar will NOT allow _____________ waves to travel through the jar. Question 4 options: sound light water
Answer:
Sound.
Explanation:
Sound requires a medium such as air to travel.
List the elements that make up the compound copper sulfate
P and Q are two substances such that the melting point of P and the boiling point of Q are the same. If P is a solid at a certain temperature, what state will Q be in at the same temperature?
Answer:
Explanation:
Firstly, it should be noted that melting and freezing points are the same. Thus, when a substance melts at a certain temperature, it means it can also start freezing/solidifying at that same temperature. That been said, when the substance P is a solid at a certain temperature, the other compound Q will boil at that same temperature and hence will be a gas at that same temperature.
If P is solid, it simply means that Q must still be in the liquid state.
From the question, we can see that, the melting point of P and the boiling point of Q are the same. The melting point of a substance is the temperature at which the solid turns to liquid while the boiling point of a substance is the temperature at which a liquid turns to a gas.
If P is solid, it simply means that Q must still be in the liquid state. It has not yet started boiling since the melting point of P and the boiling point of Q are the same.
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