Answer:
(a) Hypoeutectic
(b) Alpha solid, aluminium
(c) 70% α , 30% β
(d) 97.6% α, 2.4% β
(e) 97.6% α, 2.4% β
(f) 97% α, 3% β
Explanation:
(a) The eutectic composition for Al Si alloy is 11.7 wt% silicon, therefore, an Al-4% Si alloy is hypoeutectic
(b) For the hypoeutectic alloy, aluminium, Al, is expected to form first, such that the aluminium content is reduced till the point it gets to the eutectic proportion of 11.7 wt% silicon
(c) At 578°C we have
% α: Al (11 - 4)/(11 - 1) = 70% α
% L: Si 100 - 70 = 30% β
(d) At 576°C we have
α: 99.83% Si (99.83 - 4)/(99.83- 1.65) = 97.6% α
β: 1.65% Si (4 - 1.65)/(99.83- 1.65) = 2.4% β
(e) Primary α: 1.65% α (99.83 - 4)/(99.83 - 1.65) = 97.6% α
Eutectic 4% Si = 100 - 97.6 = 2.4% β
(f) At 25°C we have;
α%: (99.83 - 4)/(99.83 - 1) = 97% α
β%: 100 - 97 = 3% β.
How many grams of silver sulfide are formed when 0.280 g of hydrogen sulfide reacts with excess silver and oxygen?
Answer:
[tex]2.03~g~Ag_2S[/tex]
Explanation:
For this question we have to start with the reaction:
[tex]Ag~+~H_2S~+~O_2~->~Ag_2S~+~H_2O[/tex]
Now, we can balance the reaction, so:
[tex]4Ag~+~2H_2S~+~O_2~->~2Ag_2S~+~2H_2O[/tex]
With this in mind, we have to start with the amount of [tex]H_2S[/tex]. The first step is to convert from grams to moles. For this, we need to find the molar mass of [tex]H_2S[/tex]. If we check the periodic table we will find the atomic masses for Ag and H; H: 1 g/mol and A: 32 g/mol, so:
(1*2)+ (32*1) = 34 g/mol.
Now we can calculate the moles of [tex]H_2S[/tex]:
[tex]0.280~g~H_2S\frac{34~g~H_2S}{1~mol~H_2S}=0.0082~mol~H_2S[/tex]
With the moles of [tex]H_2S[/tex] we can calculate the moles of [tex]Ag_2S[/tex] if we check the molar ratio in the balanced equation, [tex]2~mol~H_2S=2~mol_Ag_2S[/tex], so:
[tex]0.0082~mol~H_2S\frac{2~mol_Ag_2S}{2~mol~H_2S}=0.0082~mol~H_2S[/tex]
With the molar mass of [tex]Ag_2S[/tex] we can convert from moles to grams (Ag: 107.86 g/mol, S: 32 g/mol), so:
(107.86*1)+(32*2)=247.80 g/mol
[tex]0.0082~mol~H_2S\frac{247.8~g~Ag_2S}{1~mol~H_2S}=2.03~g~Ag_2S[/tex]
I hope it helps!
True or False: reactions in which the oxidation state of an element decreases are reduction processes
Answer:
False; An oxidation-reduction is any chemical process that involves any chemical process in which elements undergo changes in oxidation number. hope that helps love!
The active ingredient in many commercial liquid bleaches is sodium hypochlorite. The bottle lists the percentage of sodium hypochlorite as 6.0%. If the density of commercial bleach is 1.084 g/mL, how many mL of 0.150 M sodium thiosulfate is required to reach the end point in a titration similar to the one performed in this experiment, if a student analyzed a 2.0 mL sample of bleach.
Answer:
23.3mL of 0.150M sodium thiosulfate
Explanation:
The net reaction of sodium hypochlorite (NaClO) with sodium thiosulfate (Na₂S₂O₃) is:
NaClO + 2 Na₂S₂O₃ + 2H₃O⁺ → NaCl + 3 H₂O + Na₂S₄O₆ + 2 Na⁺
2.0mL of the sample of bleach are:
2.0mL ₓ (1.084g / mL) ₓ (6 / 100) ₓ (1 mol / 74.44g) = 1.75x10⁻³ moles of NaClO
As 1 mole of NaClO reacts with 2 moles of thiosulfate:
1.75x10⁻³ moles of NaClO ₓ (2 mol Na₂S₂O₃ / 1 mol NaClO) =
3.50x10⁻³ moles of Na₂S₂O₃
If you have a 0.150M solution of thiosulfate, mL of this solution you need to reach the end point of the titration are:
3.50x10⁻³ moles of Na₂S₂O₃ ₓ (1L / 0.150mol) = 0.0233L =
23.3mL of 0.150M sodium thiosulfateWhat volume of a 3.5 M LiOH solution is needed to titrate 253 ml of a 2.75 M HF solution?
Answer:
198.8mL
Explanation:
Step 1:
Data obtained from the question:
Molarity of base (Mb) = 3.5M
Volume of base (Vb) =..?
Molarity of acid (Va) = 2.75M
Volume of acid (Va) = 253mL
Step 2:
The balanced equation for the reaction.
HF + LiOH —> LiF + H2O
From the balanced equation above,
The mole ratio of the acid (nA) = 1
The mole ratio of the base (nB) = 1
Step 3:
Determination of the volume of the base, LiOH needed for the reaction.
The volume of the base needed for the reaction can be obtained as follow:
MaVa /MbVb = nA/nB
2.75 x 253 / 3.5 x Vb = 1
Cross multiply
3.5 x Vb = 2.75 x 253
Divide both side by 3.5
Vb = 2.75 x 253 / 3.5
Vb = 198.8mL
Therefore, the volume of the base needed for the reaction is 198.8mL
Why we need blood cholesterol?
Answer:
We need blood cholesterol because our body uses it to build your structure of cell membranes, make hormones like oestrogen, and testosterone, and to help your metabolism work well.
Answer:
our cells need some cholesterol but too much cuz it can cause problems. HDL carries cholesterol to your liver, where it can be removed from the body.so it helps protect your heart from atherosclerosis
Explanation:
The number of cubic centimeters (cm) in 20.6 mL is
A) 0.0206 cm
B) 2.06 cm
I
C) 20.6 cm
D) none of these
Answer:
c
Explanation:
1 [tex]cm^{3}[/tex] = 1 mL
20,6 mL = 20,6 [tex]cm^{3}[/tex]
Answer:
C-20.6 cm^3
Explanation:
Cubic centimeters directly correspond to mL. Thus the answer would be the same as the mL
1. An isotope of cesium-137 has a half-life of 30 years. If 5.0 g of cesium-
137 decays over 60 years, how many grams will remain?
Answer:
1.25 g
Explanation:
Now we have to use the formula;
N/No = (1/2)^t/t1/2
N= mass of cesium-137 left after a time t (the unknown)
No= mass of cesium-137 present at the beginning = 5.0 g
t= time taken for 5.0 g of cesium-137 to decay =60 years
t1/2= half life of cesium-137= 30 years
Substituting values;
N/5= (1/2)^60/30
N/5= (1/2)^2
N/5= 1/4
4N= 5
N= 5/4
N= 1.25 g
Therefore, 1.25 g of cesium-137 will remain after 60 years.
7. Which molecular solid would have the lowest boiling point?
a. One that has hydrogen bonding
b. One made of molar molecules
c. One with dipole-dipole attractions
d. One with induced dipole attractions
Answer:
The molecular solids would have the lowest boiling point because of WEAK INTERMOLECULAR FORCES.
Explanation:
Answer: One with induced dipole attractions
Aluminum has a density of 2.70 g/mL. Calculate the mass (in grams) of a piece of aluminum having a volume of 374 mL. Express your answer to three significant figures.
Answer:
Explanation:I don't say u must have to mark my ans as brainliest but if it has really helped u plz don't forget to thnk me...
Erbium (Er) is element 68 on the periodic table. A sample contains 5.04×1023 atoms of Er. Calculate the amount of Er.
Answer:
139.98 g to nearest hundredth.
Explanation:
Using Avogadro's Number:
One mole (167.26 g) of Erbium equates to 6.022141 * 10^23 atoms.
So 5.04 * 10^23 = 167.26 * 5.04/6.022141
= 139,98 g.
A maple tree could be studied in many fields of science. What aspect of a maple tree might be studied in chemistry
Answer:
botany because a maple tree is a plant
Explanation:
A gas sample has a pressure of 2.65 atm when the temperature is -18 ∘C. What is the final pressure, in atmospheres, when the temperature is 39 ∘C, with no change in the volume or amount of gas?
Answer:
P₂ = 3.24atm
Explanation:
the amount of order in an isolated system cannot increase; it may only stay the same or decrease. This expresses which of the following?
Conservation of mass
The First Law of Thermodynamics
The second Law of Thermodynamics
Kinetic Theory
The definition of work
the definition of heat
Answer:
Second law of thermodynamics.
Explanation:
Second law of thermodynamics states the entropy or order in an isolated system always increases. The isolated system evolve spontaneously toward thermal thermal equilibrium.
For example if a room is untidy and dirty,it will become messy over time and disorder. So when the room is cleaned, there won't be disorderliness and entropy will decrease.
The pressure gauge on a tank registers the gauge pressure, which is the difference between the interior pressure and exterior pressure. When the tank is full of oxygen (O2), it contains 15.0 kg of the gas at a gauge pressure of 36.0 atm. Determine the mass of oxygen that has been withdrawn from the tank when the pressure reading is 21.6 atm. Assume the temperature of the tank remains constant.
Answer:
GOOD DAY ON YOUR QUIZ
Explanation:
Al2O3 would be typed in as Al2O3 Al2(SO4)3 would be typed in as Al2(SO4)3.
Required:
a. Write the formula for calciumnitride.
b. Write the formula for magnesium phosphide
c. Write the formula for rubidium chromate
d. Write the formula for aluminum nitrate
e. Write the formula for ammonium arsenide
f. Write the formula for nickel(II) nitrite
g. Write the formula for copper(I) sulfate
h. Write the formula for iron(III) nitrate
i. Write the formula for manganese(II) nitride
Answer:
Explanation:
Hello,
We are required to write the chemical formula of the following compounds
1. Calcium nitride = Ca₃N₂
2. Magnesium Phosphide = Mg₃P₂
3. Rubidium Chromate = Rb₂CrO₄
4. Aluminium nitrate = Al(NO₃)₃
5. Ammonium Arsenide = (NH₄)₃As
6. Nickel(ii) nitrite = Ni(NO₂)₂
7. Copper(i)sulfate = Cu₂SO₄
8. Iron(iii)nitrate = Fe(NO₃)₃
9. Manganese(ii)nitrate = Mn(NO₃)₂
The left hand side are the common names when the right hand side are the chemical formula.
Addition of an excess of lead (II) nitrate to a 50.0mL solution of magnesium chloride caused a formation of 7.35g of lead (II) chloride precipitate. What was the molar concentration of chloride ions in the solution (in mol/L)?
Answer:
[Cl⁻] = 0.016M
Explanation:
First of all, we determine the reaction:
Pb(NO₃)₂ (aq) + MgCl₂ (aq) → PbCl₂ (s) ↓ + Mg(NO₃)₂(aq)
This is a solubility equilibrium, where you have a precipitate formed, lead(II) chloride. This salt can be dissociated as:
PbCl₂(s) ⇄ Pb²⁺ (aq) + 2Cl⁻ (aq) Kps
Initial x
React s
Eq x - s s 2s
As this is an equilibrium, the Kps works as the constant (Solubility product):
Kps = s . (2s)²
Kps = 4s³ = 1.7ₓ10⁻⁵
4s³ = 1.7ₓ10⁻⁵
s = ∛(1.7ₓ10⁻⁵ . 1/4)
s = 0.016 M
In the Hall-Heroult process, a large electric current is passed through a solution of aluminum oxide dissolved in molten cryolite , resulting in the reduction of the to pure aluminum. Suppose a current of is passed through a Hall-Heroult cell for seconds. Calculate the mass of pure aluminum produced. Round your answer to significant digits. Also, be sure your answer contains a unit symbol.
The given question incomplete, the complete question is:
In the Hall-Heroult process, a large electric current is passed through a solution of aluminum oxide (Al,03) dissolved in molten cryolite (Na, Alts).re in the reduction of the Al, o, to pure aluminum. Suppose a current of 1800. A is passed through a Hall-Heroult cell for 37.0 seconds. Calculate the mass of pure aluminum produced Be sure your answer has a unit symbol and the correct number of significant digits.
Answer:
The correct answer is 6.2114 grams.
Explanation:
Based on the given question, the value of current or I have given is 1800 amperes, the time given is 37 seconds, and there is a need to find the mass of the pure aluminum generated in the process. Mass or weight can be determined by using Faraday's first law equation, that is, w = MIt/nF.
Here, M is the atomic mass, w is the weight of the substance deposited, t is time, I is current, n is the number of moles of the electron, and F is the Faraday's constant, which is 96500 C. In the process mentioned in the question, aluminum oxide is reduced to give rise to pure aluminum, and in the process 3 electrons are gained. So, the value of n will be 3. The M or the atomic mass of Al is 27 gm per mole. Now putting the values in the equation we get,
w = 27*1800*37 / 3*96500
w = 1798200 / 289500
w = 6.2114 grams
Hence, pure aluminum produced in the process is 6.2114 grams.
When a 20.0 g sample of an unknown compound is dissolve in 500. G of benzene, the freezing point of the resulting solution is 3.77 o C. The freezing point 9f pure benzene is 5.48 o C and Kf for benzene is 5.12 o C/m. Calculate the molar mass of the unknown
Answer:
The correct answer is 116.3 g/mol
Explanation:
When a solute is added to a solvent, the freezing point decreases. That is called freezeing point depression and is given by the following expression:
ΔTf= Kf x m
Where ΔTf is the decrease in freezing point (final temperature - initial temperature), Kf is the freezeing point constant, m is the molality of the solution.
We have the following data:
Kf= 5.12ºC/m
ΔTf= 5.48ºC - 3.77ºC = 1.71ºC
We can calculate the molality of the solution from the mathematical expression for freezeing point as follows:
m = ΔTf/Kf = 1.71ºC/(5.12º C/m)= 0.334 m
The molality is the number of moles of solute in 1 kg of solvent. The solute was added to 500 g of solvent (benzene), so we can multiply the molality by the grams of solvent (500 g = 0.5 kg) to obtain the number of moles:
0.334 mol/kg x 0.5 kg = 0.172 moles
We know that the molar mass is equal to the mass of compound per mole, so we divide the mass into the moles to obtain the molar mass as follows:
MM = mass/moles= 20.0 g/0.172 moles = 116.3 g/mol
Ashley notice that the mineral appear metallic under the light. What property was actually measuring?
Answer: The property is called Luster
Explanation:
Luster is a term used to describe the appearance of light from the surface of the mineral when it reflects light. The two types of classification of Luster is Mettalic or Non Mettalic.
some examples of minerals with mettalic lustre are --- Galena, graphite, Gold, Silver, Copper etc
Some examples of minerals with non mettalic lustre are--- Barite, Serpentine, Fluorite etc.
Answer:
Lustrous property
Explanation:
Materials like metals that have lustre usually glow or display sheen when light comes in contact with the surface of the material.
It is derived from the Latin word "lux" meaning "light", which is indicative of radiance or gloss.
Lustre is a common property of metals, including sonourousity, malleability and ductility amongst others.
Identify which subatomic particles match each of these descriptions. One of the descriptions describes two particles. Make sure to include both particles it describes.
Description Particle(s)
have a relative charge of +1
have a relative charge of −1
have no charge
located in the nucleus of an atom
have a much lower mass than the other two types of particles
Explanation:
First off, it's important to know that the three subatomic particles we have are the proton, neutron and electron.
have a relative charge of +1 : This is the proton. It is the postive subatomic particle present in an atom.
have a relative charge of -1 : This is the electron. It is the negative subatomic particle present in an atom.
have no charge : This is the neutron. It is the neutral subatomic particle present in an atom.
located in the nucleus of an atom : Twoo subatomic particles are located in the nucleus, the neutron and proton.
have a much lower mass than the other two types of particles: This is the electron. The proton and neutron are almost similar in mass. The electron is abut 1 / 1840 times the mass of the proton.
Based on its location on the periodic table, how many electrons does nitrogen have in its outer energy level?
Answer:
its 5 got it right
Water is intentionally present in a state where its molecules are far apart during a change of state is molecule slow down which change of state has most likely taking place
Answer:
melting
Explanation:
A sample of sulfuryl fluoride, SO2F2, has a mass of 19.2 g. What amount, in moles, does this mass represent?
Answer:
0.188 moles
Explanation:
moles=mass/molar mass
moles= 19.2/ (32+32+38)
moles= 0.188
Answer:
0.188 moles.
Explanation:
Molar mass of SO2F2
= 32 + 2*16 + 2 * 19
= 102 g.
So 19.2g = 19.2 / 102
= 0.188 moles.
Explain why airborne and water-borne chemicals are both local and global issues.
The force that moves sediment in a landslide or mudflow is _.
Answer:
Erosion.
Explanation:
Erosion is the act of loose soil crumbling under itself and causes it to slide down a hill.
Answer:
erosion
Explanation:
Why LDL called "bad" cholesterol?
Answer:
Its called bad cholesterol because a high LDL level leads to buildup of cholesterol in your arteries.
Explanation:
Which of the following is a characteristic of the lanthanides?
O A. They are silvery metals that conduct electricity.
B. There are no known uses for the metals.
C. They are all radioactive.
D. They are used in making fireworks
Answer:
A
Explanation:
Lanthanides share the following common properties: Silvery-white metals that tarnish when exposed to air, forming their oxides. Relatively soft metals. Hardness increases somewhat with higher atomic number.
Answer:
APEX
Explanation:
A
Sodium metal and water react to form hydrogen and sodium hydroxide. If 11.96 g of sodium react with water to form 0.52 g of hydrogen and 20.80 g of sodium hydroxide, what mass of water was involved in the reaction
Answer:
9.36g of H2O.
Explanation:
We'll begin by writing the balanced equation for the reaction.
2Na + 2H2O —> 2NaOH + H2
Next, we shall determine the mass of Na and H2O that reacted from the balanced equation.
This is illustrated below:
Molar mass of Na = 23g/mol
Mass of Na from the balanced equation = 2 x 23 = 46g
Molar mass of H2O = (2x1) + 16 = 18g/mol
Mass of H2O from the balanced equation = 2 x 18 = 36g
From the balanced equation above,
46g of Na reacted with 36g of H2O.
Now, we can determine the mass of H2O involved in reaction as follow:
From the balanced equation above,
46g of Na reacted with 36g of H2O.
Therefore, 11.96g of Na will react with = (11.96 x 36)/46 = 9.36g of H2O.
Therefore, 9.36g of H2O were used for the reaction.
A football field is 120 yards by 53.333 yards. What is the area of the football field in acres if 1 acre=43560 ft?? Use correct
significant figures when answering this question.
Answer:
1.3223 acres
Explanation:
a football field's area is 360 feet (120 yards) x 160 feet (53.333 yards) = 57,600 sq. feet
if the area of an acre is 43,560 sq. feet, then a football field in acres = 57,600 sq. feet / 43,560 sq. feet = 1.3223 acres
we can verify our answer by doing the same calculation in sq. yards:
football field = 120 yards x 53.33 yards = 6,400 sq. yards
an acre is 4,840 sq. yards
football field in acres = 6,400 sq. yards / 4,840 sq. yards = 1.3223 acres
The area of the field is 1.3223 acres
From the question given above, the following data were obtained:
Dimension = 120 yard × 53.333 yard
Area =?The area of the field can be obtained as follow:
Area = Dimension
Area = 120 yard × 53.333 yard
Area = 6399.96 yard²Finally, we shall convert 6399.96 yard² to acre. This can be obtained as follow:
4840 yard² = 1 acre
Therefore,
6399.96 yard² = 6399.96 / 4840
6399.96 yard² = 1.3223 acresThus, the area of the field is 1.3223 acres
Learn more: https://brainly.com/question/1406215
There is a container on the lab bench containing some unknown chemical. You should:
a. Dump it, wash the glassware. Some people are slobs.
b. Move it out of the way in case it is dangerous. Otherwise, not your problem.
c. Leave it. The rightful owner will claim it eventually.
d. Tell your lab supervisor.
Answer:
D
Explanation:
Your supervisor is in charge of you so therefore you must always tell your supervisor first.
Answer:
C.
Explanation:
Because you might get hurt, could be dangerous.