Answer:
Explanation:
The balanced equation says that we'll get 1 mole of H2 for every 1 mole of Mg. 50 grams of H is 50g/2 g/mole = 25 moles of H2. That means we'll need 25 moles of Mg. Convert that into grams: (25 moles Mg)*(24.3 g/mole) = 607 grams Mg.
At STP, all gases occupy 22.4 liters/miole. That means 25 moles of H2 would occupy (25 moles)*(22.4 liters/mole) = 560 liters.
Which is the formula for nitrogen trihydride? NH3 N3H 3NH N3H3
the answer isssssssssssssssssssssss... Nh3.
Answer: A.) NH3
Explanation:
The half-life of a radioactive substance is 15 days. After 10 days a sample of the substance has been reduced to a mass of 4 mg. A. What was the inital mass (in mg) of the sample? B. Using your answer from above, after how many days will there only be 0. 3 mg of substance left?.
A. The initial mass of the sample is 6.35
B. The time taken for 0.3 mg of the sample to remain is 66 days
A. Determination of the initial mass of the sample
We'll begin by calculating the number of half-lives that has elapsedHalf-life (t½) = 15 days
Time (t) = 10 days
Number of half-lives (n) =?n = t / t½
n = 10 / 15
n = ⅔Finally, we shall determine the initial mass of the sample.Number of half-lives (n) = ⅔
Amount remaining (N) = 4 mg
Initial amount (N₀) =?[tex]N_0 = N \times {2}^{n} \\ N_0 = 4 \times {2}^{2 \div 3} \\ N_0 = 6.35 \: mg[/tex]
Therefore, the initial mass of the sample is 6.35 mg
B. Determination of the time
We'll begin by calculating the number of half-lives that has elapsedAmount remaining (N) = 0.3 mg
Initial amount (N₀) = 6.35 mg
Number of half-lives (n) =?[tex]{2}^{n} = \frac{N_0}{N} \\ \\ {2}^{n} = \frac{6.35}{0.3} \\ \\ {2}^{n} = 21.167 \\ take \: the \: log \: of \: both \: side \\ log \: {2}^{n} = log \: 21.167 \\ nlog2 = log \: 21.167 \\ divide \: both \: side \: by \: log2 \\ \\ n = \frac{log \: 21.167}{log2} \\ \\ n = 4.4[/tex]
Finally, we shall determine the timeNumber of half-lives (n) = 4.4
Half-life (t½) = 15 days
Time(t) =?t = n × t½
t = 4.4 × 15
t = 66 daysTherefore, it will take 66 days for 0.3 mg of the sample to remain.
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please help due right now
10 POINTS
Answer:
F=ma
Explanation:
F=m×a
according to that F÷m=a and also F ÷a=m
Describe how the suspects used the chemicals found at the crime scene to make the copper coins look silver.
The chemicals found at the crime scene although not mentioned must be Sodium zincate.
Discussion:
An interesting demonstration to show plating and alloys is the conversion of copper coins to silver look-alike coins.
A 'copper' coin when dipped into a solution of sodium zincate in contact with zinc. The coin is plated with zinc and appears silver in colour.
This is a common chemistry classroom trick.
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What is the differences between solids liquids and gases on a molecular level apes.
True or false: For a spontaneous redox reaction, the products are stronger oxidizing and reducing agents than the reactants.
Answer: False
Explanation: The stronger oxidizing agent, and stronger reducing agent are the reactants.
The given statement is false , for a spontaneous redox reaction, the reactants are stronger oxidizing and reducing agents than the products.
What are redox reactions?Redox reactions comprise of two parts a reduced part and an oxidized part, which occur simultaneously . The part which is reduced gain electrons and hence there is a increase in oxidation state of the species.
While, the part which is oxidized looses electrons and hence there is a decrease in oxidation state of the species.During redox reactions, there is no net change in the number of electrons . Electrons which are given off in oxidation are used up in reduction.
The ion or molecule which accepts electrons is called as oxidizing agent while the ion or molecule which donates electrons is called as a reducing agent.
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How do mixtures differ from substances?
Answer:
In chemistry: a pure substance consists only of one element or one compound. a mixture consists of two or more different substances, not chemically joined together.
Hope this helps :)
How many moles of atoms are in 3.00 g of 13^C?
Answer:
1) 1.39 * 10²³ atoms
Explanation:
A student dissolved some crystals of a salt in water.
The student added sodium hydroxide solution to the salt solution
The student added sodium hydroxide until it was in excess
Describe what the student would see if the salt contained calcium ions
Under Normal Conditions no reaction will be seen between Calcium ions (Ca⁺), NaCl (salt solution) and NaOH(sodium hydroxide).
What is a double replacement reaction ?In a double replacement reaction , the compounds present switch cation and anion to form new compounds.
But here in NaOH(sodium hydroxide) and NaCl (salt solution) the cation sodium ion Na⁺, of both the compounds is same so the end result will be same .
There will be no net reaction .
But if excess Sodium Hydroxide is added to the solution , we will see precipitate of NaCl , salt forming.
If Salt contained Ca⁺ ions , firstly NaCl will only combine with Ca⁺ ions in special conditions as Na⁺ ions are more reactive than Ca⁺ ions.
On addition of NaOH we would observe no change in normal conditions due to above stated reason .
In special conditions following reaction takes place ,in normal condition the reaction follows reverse direction.
Ca + 2 NaOH ← Ca(OH)₂ + 2 Na
Hence under Normal Conditions no reaction will be seen between Calcium ions , NaCl (salt solution) and NaOH(sodium hydroxide).
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how can teh human body looose heat? (conduction, convecion, radiation) and WHY
Answer:
Radiation and conduction
Explanation:
The human body lose heat by these two ways, because everything that touches our bodies and is in a temperature below us will receive part of our heat (conduction), and you can figure out that we lose heat by radiation because a human bright in a heat cam
Write the balanced chemical equation for the reaction
of solid carbon with oxygen gas to form carbon monoxide gas.
Answer:
2C +O2 - COExplanation:
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The balanced chemical equation for the reaction of solid carbon with oxygen gas to form carbon monoxide gas is 2 C + O₂[tex]\rightarrow[/tex] 2 CO.
What is chemical equation?Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.
A plus sign is present between reactants and products if they are more than one in any case and an arrow is present pointing towards the product side which indicates the direction of the reaction .There are coefficients present next to the chemical symbols and formulas .
The first chemical equation was put forth by Jean Beguin in 1615.By making use of chemical equations the direction of reaction ,state of reactants and products can be stated. In the chemical equations even the temperature to be maintained and catalyst can be mentioned.
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What are the two ways in which cellular processes can be regulated?
Answer:
Homeostasis to photosynthesis and anaerobic respiration to aerobic respiration.
what is the name of the high-energy compound that cells use to fuel chemical reactions?
Answer: Adenosine triphosphate, or ATP, is the primary carrier of energy in cells. The water-mediated reaction known as hydrolysis releases energy from the chemical bonds in ATP to fuel cellular processes.
Explanation:
Why does water freeze at a temperature lower than 0°c when salt is added to it.
Answer:
Salt molecules block water molecules from packing together when temperature is lowered. It then prevents them from becoming ice. More water molecules leave the solid phase than the ones entering the solid phase. Freezing point depression occurs when the freezing point of the liquid is lowered by addition of solute.
Explanation:
Give 2 reason why cryolite is used
what makes your pulse? Explain
A solution containing cacl2 is mixed with a solution of li2c2o4 to form a solution that is 2. 1*10^-5m in calcium ion and 4. 75*10-5 m in oxalate ion. What will happen once these solutions are mixed?\.
Answer:
the answer is d
Explanation:
i know
Where do you think the atoms for plant growth come from?
Answer:
the mass of a tree is primary carbon
Explanation:
the the carbon comes from carbon dioxide during photosynthesis
Answer:
Plants get all the carbon, hydrogen, and oxygen they need from carbon dioxide and water, which they use to build carbohydrates during photosynthesis. To build other kinds of molecules they also need elements like nitrogen, phosphorous, and sulfur. Plants get these as well as other elements from the soil.
Explanation:
An ________________ is the smallest unit of matter that retains all of the chemical properties of an element.
Answer: Atom
..............................................
The diagram shows fertilization, the union of sperm cell and egg cell.
The traits of the offspring of the fertilized egg are coded onto
A
lipids in the offspring's cell membranes.
B
enzymes in the offspring's ribosomes.
C
genes in the offspring's chromosomes.
D
water in the offspring's mitochondrion.
mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron. carbon. plastic. glass.
Mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron.
What is iron?The chemical element iron has the atomic number 26 and the symbol Fe. It is a metal that is found in group 8 of a periodic table and the first transition series. It makes up a large portion of the planet's outer or inner core and is the most prevalent element on Earth by mass, just ahead of oxygen.
It is the fourth most prevalent element in the crust of the Earth, having been mostly deposited by meteorites inside its metallic state, along with its ores. Iron ores must be processed in kilns or furnaces that may reach 5000 °C (2,730 °F) and higher, which is approximately 500 °C (932 °F) greater than the temperature needed to smelt copper. Mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron.
Therefore, mr. garcia uses magnets to hold a poster on a steel filing cabinet because a main component of steel is iron.
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How to find formula for ionic compounds.
Answer:
I am using an example for this in this table it works for any other compound as well.
How many grams of solid sodium acetate should be added to 2.00 L of 0.184 M acetic acid solution to prepare a buffer with a pH of 4.140
pH = pKa + log [NaAc]/[HAc]
4.140 = 4.74 + log x
log x = -0.60
x = [NaAc]/[HAc] = 0.25
moles HAc = 1.50 L x 0.287 mol/L = 0.431 moles
moles NaAc = 0.25 x 0.431 = 0.1078 moles NaAc
grams NaAc = 0.108 x 80 g/mole = 8.64 grams
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How does a phase change from solid to liquid occur in a substance?(1 point)
Answer:
As heat is added to solid water, the temperature increases until it reaches 0 °C, the melting point. At this point, the phase change, added heat goes into changing the state from a solid to liquid. Only when this phase change is complete, the temperature can increase.
hope this helps
Heat is responsible for the change of phase from solid to liquid state.
A phase change from solid to liquid occur in a substance by heating of that substance because the bonds present between solid particles can be broken down with the help of heat energy.
When the bond is heat at the temperature on which it is broken down, the solid particles are converted into liquid substance so we can conclude that heat is responsible for the change of phase from solid to liquid state.
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what element is 1s2 2s2 2p3
which value represents the first ionization energy of a nonmetal
Answer:
increase in going from left to right across a given period.
Explanation:
Nonmetals, which are found in the right-hand region of the periodic table, have relatively large ionization energies and therefore tend to gain electrons. Ionization energies generally increase in going from left to right across a given period.
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Which of these elements would have an electron affinity higher than that of oxygen?
Li
Ca
Ne
C
Be
Answer: Ne ( Neon )
Explanation: Lithium ( Li ), beryllium ( Be ), carbon ( C ), oxygen ( O ), and neon ( Ne ), are all in Period 2 in that order. Sodium ( Na ) is in Period 3. Since electron affinities decrease as you go down, Na would have a lower electron affinity level then Li but since electron affinities increase as you go across a period, only neon is farther right then oxygen ( O ), so it would be the only one element of this group that would have a higher electron affinity than that of oxygen.
There are various kind of elements that are present in periodic table. Some elements are harmful, some are radioactive, some are noble gases. Option C is correct option.
What is periodic table?Periodic table is a table in which we find elements with properties like metals, non metals, metalloids and radioactive element arranges in increasing atomic number.
Periodic table help a scientist to know what are the different types of elements are present in periodic table so that they can discover the new elements that are not being discovered yet.
On going down the group electronegativity decreases. On going along the period the electronegativity increases. So, Neon lies on the extreme right of Fluorine in the same period. Neon will have more electronegativity than oxygen.
Therefore, Neon is more electronegativity than fluorine.
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A car starts from rest and accelerates at 2.5m/s^2 for 2s. What is the final velocity of the car
[tex]\begin{gathered}\boxed{\begin{array}{c}\\ {\pmb{\sf{Three \: equation \: of \: motion}}} \\ \\ \sf \star \: v \: = u \: + at \\ \\ \sf \star \: s \: = ut + \: \dfrac{1}{2} \: at^2 \\ \\ \sf \star \: v^2 - u^2 \: = 2as\end{array}}\end{gathered}[/tex]
Calculation :-[tex]\pink{\qquad \pmb{ \sf\longrightarrow v \: = u \: + at}}[/tex]
[tex] \qquad \pmb{\sf \longrightarrow v = 0 + 2.5 \times 2}[/tex]
[tex]\qquad \pmb{ \sf\longrightarrow v = 0 + 5}[/tex]
[tex] \qquad \pmb{\sf \longrightarrow v = 5 \: ms^{-1}}[/tex]
[tex]\qquad \longrightarrow {\pink{\underline{\underline{\pmb{\sf{ Final \: velocity= 5 \: ms^{-1} }}}}}}[/tex]
Henceforth –
The final velocity of the car is 5 m/s▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
Find the number of CO2 molecules present in 20l of CO2 at 0°C and 772mm of Hg.
I wiLL mark you as brainliest and give 50 points.
Answer:
18
At STP, 22.4 liters of a gas forms one mole that is 6.023×10
23
molecules.
Volume of CO
2
in 1 litre of air =
100
0.03
×1 L
∴ No. of molecules of CO
2
=
22.4
6.023×10
23
×
100
0.03
=8.066×10
18
Explanation:
I guess it's this
[tex]\\ \sf\longmapsto PV=nRT[/tex]
[tex]\\ \sf\longmapsto n=\dfrac{PV}{RT}[/tex]
[tex]\\ \sf\longmapsto n=\dfrac{772(20)}{8.314(273)}[/tex]
[tex]\\ \sf\longmapsto n=\dfrac{15440}{2269.722}[/tex]
[tex]\\ \sf\longmapsto n=6.8mol[/tex]
