Answer:
0. 070g
Mass of 1 Si atom =28.08/6.022*1023
So mass 1.5 *1021*4.6629*10-23
Answer:
[tex]\boxed {\boxed {\sf 0.070 \ g \ Si}}[/tex]
Explanation:
We are given a value of atoms and asked to find the mass. We can complete this in 2 steps.
1. Convert Atoms to Moles
First, we have to convert atoms to moles. We use Avogadro's Number or 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance.
In this case, the particles are silicon atoms. We can set up a proportion.
[tex]\frac { 6.022 \times 10^{23} \ atom \ Si }{1 \ mol \ Si}[/tex]
Multiply by the value of atoms given.
[tex]1.5 \times 10^{21} \ atom \ Si *\frac { 6.022 \times 10^{23} \ atom \ Si }{1 \ mol \ Si}[/tex]
Flip the ratio. This allows the atoms of silicon units to cancel and leave the moles of silicon.
[tex]1.5 \times 10^{21} \ atom \ Si *\frac {1 \ mol \ Si } {6.022 \times 10^{23} \ atom \ Si}[/tex]
[tex]1.5 \times 10^{21}*\frac {1 \ mol \ Si } {6.022 \times 10^{23} }[/tex]
[tex]\frac {1.5 \times 10^{21} \ mol \ Si } {6.022 \times 10^{23} }[/tex]
[tex]0.002490866822 \ mol \ Si[/tex]
2. Convert Moles to Grams
Next, we convert the moles to grams. We use the molar mass, which is found on the Periodic Table. This value is the number of grams in 1 mole of a substance. Look for silicon (Si).
Si: 28.085 g/molUse this value as a ratio.
[tex]\frac {28.085 \ g \ Si}{1 \ mol \ Si}[/tex]
Multiply by the number of moles we calculated.
[tex]0.002490866822 \ mol \ Si *\frac {28.085 \ g \ Si}{1 \ mol \ Si}[/tex]
The moles of silicon units cancel, so we are left with grams.
[tex]0.002490866822 *\frac {28.085 \ g \ Si}{1}[/tex]
[tex]0.002490866822 *{28.085 \ g \ Si}[/tex]
[tex]0.06995599469 \ g \ Si[/tex]
3. Round
Finally we must round our answer. The original value has 2 significant figures, so our answer must have the same. For the number we calculated, that is the thousandth place.
[tex]0.069\underline95599469 \ g Si[/tex]
The 9 tells us to round the other 9 to a 0, then the 6 to a 7.
[tex]0.070 \ g \ Si[/tex]
The mass of 1.5 × 10²¹ silicon atoms is 0.070 grams of silicon.
The temperature of 100. g of water at 25.0C increases to 31.9C. How much energy was added to the water? The specific heat of water is 4.184J/gC.
Answer:
2890j
Explanation:
20. Identi
21. Name the process and explain what is occurring at D.
Answer:
At D: Soil erosion us the process taking place.
Soil erosion is the washing away of the Earth's or soil's top layer by eroding agents.
If the solubility of sodium chloride is 36 grams per 100 grams of water, which of the following solutions would be considered unsaturated? If the solubility of sodium chloride is 36 grams per 100 grams of water, which of the following solutions would be considered unsaturated? 3.25 moles of NaCl dissolved in 500 ml of water 1.85 moles of NaCl dissolved in 300 ml of water 5.8 moles of NaCl dissolved in 1 L of water none of the above
Answer: If the solubility of sodium chloride is 36 grams per 100 grams of water then 5.8 moles of NaCl dissolved in 1 L of water solution would be considered unsaturated.
Explanation:
A solution which contains the maximum amount of solute is called a saturated solution. Whereas a solution in which more amount of solute is able to dissolve is called an unsaturated solution.
Now, the number of moles present in 36 g of NaCl (molar mass = 58.4 g/mol) is as follows.
[tex]No. of moles = \frac{mass}{molar mass}\\= \frac{36 g}{58.4 g/mol}\\= 0.616 mol[/tex]
This shows that solubility of sodium chloride is 36 grams per 100 grams of water means a maximum of 0.616 mol of NaCl will dissolve in 100 mL of water.
So, a solution in which number of moles of NaCl are less than 0.616 mol per 100 mL then the solution formed will be an unsaturated solution.
As 5.8 moles of NaCl dissolved in 1 L (or 1000 mL) of water. So, moles present in 100 mL are calculated as follows.[tex]Moles = \frac{5.8 mol}{1000 mL} \times 100 mL\\= 0.58 mol[/tex]
Moles present in 100 mL of water for 3.25 moles of NaCl dissolved in 500 ml in water are as follows.[tex]Moles = \frac{3.25 mol}{500 mL} \times 100 mL\\0.65 mol[/tex]
Moles present in 100 mL of water for 1.85 moles of NaCl dissolved in 300 ml of water are as follows.[tex]Moles = \frac{1.85 mol}{300 mL} \times 100 mL\\= 0.616 mol[/tex]
Thus, we can conclude that if the solubility of sodium chloride is 36 grams per 100 grams of water then 5.8 moles of NaCl dissolved in 1 L of water solution would be considered unsaturated.
Steve and Meg are doing an experiment where they need to make 37 grams of Fe2O3. How many grams of Fe would they need ?
Answer:
25.9g
Explanation:
Molecular mass of Fe₂O₃ = (56 * 2) + (16 * 3)
= 112 + 48 = 160
Let's follow the unitary method now
In 160g Fe₂O₃ , there is 112 g Fe
In 1 g Fe₂O₃ , there is 112 / 160 g Fe
In 37 Fe₂O₃ , we need 112 * 37 / 160
= 25.9 g Fe
Water is an essential molecule to life on Earth. Which of the following is not a property of water that is critical to biological life?
1. surface tension
2. density
3. temperature
4. viscosity
The property of water that is not critical to biological life is surface tension.
What is biological life?Biological life means the life in which living organism do exist and for their survival they mainly depends on water and air.
The main critical properties that water should posses to biological life are density, temperature, cohesive force and adhesive force. Viscosity is also understand by the cohesive force because more attraction between atoms more viscous they are.
Hence option (1) is correct i.e. surface tension.
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keeping a bike indoor will stop it rusting true or false
Answer: True because if you leave it outside and it rains on the bike it will cause rust. Keep it in the garage or something. :) I have a bike btw.
Explanation:
The best way to prevent rusting is to store your bike safely away when it isn't being used and apply a rust-proofing lubricant to protect it when you are riding it – enjoying those wet and wild rides guilt-free!
so true
The equation H2 + O2 -> H2O is unbalanced. When balanced, what is the correct coefficient for O2?
Answer:
The balanced equation would be 2H2 + O2 -> 2H2O
Explanation:
The correct balanced equation is 2H₂ + O₂ → 2H₂O, and the correct coefficient for O₂ is 1.
How to balance a chemical equation?Count the atoms on each side first. Next, alter one of the compounds' coefficient. Third, count the atoms once more, and then repeat steps two and three until the equation is balanced.
In the given equation, hydrogens are already balanced. To balance oxygen, multiple water with 2. Thus, equation becomes:
H₂ + O₂ → 2 H₂O
Now, oxygen is balanced, just the hydrogens got unbalanced. To balance hydrogen, multiply the hydrogen by 2 on the left side.
2 H₂ + O₂ → 2H₂O
Now the chemical equation is balanced, in which the number of oxygen and hydrogen are equal on both sides of the arrow.
Therefore, the coefficient of O₂ is 1.
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What is TRUE about the majority of explosives that forensic scientists deal with in investigations?
А.
They are made of dynamite and TNT.
B.
They are Molotov cocktails.
C. They use high explosives.
D.
They are homemade bombs.
Answer:D
Explanation:
The majority of explosives that forensic scientists deal with in investigations are homemade bombs. Therefore, option D is correct.
What are forensic scientist ?In general, forensic scientists do the following kinds of work: They examine tangible materials gathered from crime sites. They offer forensic expert testimony both before and during court proceedings. Blood, hair, and other trace evidence are gathered by investigators and sent to crime labs for analysis.
Criminalists or crime scene investigators are generalist forensic science technicians that gather evidence at the scene of a crime and conduct scientific and technical examination in labs or offices.
A forensic scientist's key responsibilities include gathering evidence at the crime scene, documenting the findings in reports, processing the evidence at the lab, and giving testimony in court.
Thus, option D is correct.
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The diagram shows that the boiling point of water is 100°C At a pressure of one atm.
How could you reduce the boiling point of water in this system?
A. Increase the size of the flame
B. Decrease the volume of the water
C. Decrease the pressure to 0 atm.
D. Increase the pressure to 2 atm
Answer:
I think the answer will be number A
The boiling point of a substance is constant and for water it is 100 degree celsius. However by reducing the surrounding pressure the boiling point can be reduced.
What is boiling point ?Boiling point of a substances is the temperature at which the vapor pressure of the gas phase above the liquid equals to the atmospheric pressure where, the liquid converts to the vapor state.
Boiling point depends on the bond type, molar mass, temperature and pressure. As the and pressure increases, boiling point increases. Similarly with an increasing mass and more strength intermolecular force results in greater boiling point.
As the atmospheric pressure decreases, the temperature needed to equalise the vapor pressure of the gas phase over the liquid also decreases. Hence, boiling point decreases. Therefore, option C is correct.
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What is the fundamental different between combustion and nuclear reaction
Answer:
Nuclear reactions involve a change in an atom's nucleus, usually producing a different element. Chemical reactions, on the other hand, involve only a rearrangement of electrons and do not involve changes in the nuclear.
Your friend had an upset stomach caused by indigestion. His mother explained to him
that indigestion is when the contents in the stomach are too acidic. She also told him to
drink soda to settle his stomach. The soda did not help. You tell him that you would not
have expected the soda to help with the indigestion based on what you know about
acids and bases.
ليالي
Baking Soda
Acidic
Neutral
Basic
Explain why soda would not help settle your friend's stomach. In your reponse, be sure
to include:
• a better alternative to drinking soda.
• how each substance above would react with the stomach acid.
• defining characteristics of acids and bases, besides how they react.
Be sure to consider the completeness of your response, supporting details, and accurate
use of terms.
Answer:
because it may cause burn that causes acid to build up which causes you to keep having an upset stomach
please answer asap!
What is the molarity of a KOH solution if 200 ml of the solution contains 0.6 moles KOH?
a. 0.3 M
b. 0.6 M
c. 3.0 M
d. 6.0 M
If you are given 96.0 grams of O2, how many grams of H20 are made?
Answer:
10.66 grams
Explanation:
Can someone please help me, i just need help =(
Answer:
The answers to your questions are given below
Explanation:
F. Determination of the missing part of the equation.
_ I₂ + _Na₂S₂O₃ —> _ NaI + _ Na₂S₄O₆
The above equation can be balance as illustrated below:
I₂ + Na₂S₂O₃ —> NaI + Na₂S₄O₆
There are 2 atoms of I on the left side and 1 on the right side. It can be balance by writing 2 before NaI as shown below:
I₂ + Na₂S₂O₃ —> 2NaI + Na₂S₄O₆
There are 2 atoms of Na on the left side and a total of 4 atoms on the right side. It can be balance by writing 2 before Na₂S₂O₃ as shown below:
I₂ + 2Na₂S₂O₃ —> 2NaI + Na₂S₄O₆
Now the equation is balanced.
The coefficients are: 1, 2, 2, 1
Elements >>> Reactant >>> Product
Sodium >>>>> 4 >>>>>>>>> 4
Sulphur >>>>> 4 >>>>>>>>> 4
Oxygen >>>>> 6 >>>>>>>>> 6
Iodine >>>>>> 2 >>>>>>>>>> 2
G. Determination of the missing part of the equation.
__ Mg + __P₄ —> __Mg₃P₂
The above equation can be balance as illustrated below:
Mg + P₄ —> Mg₃P₂
There are 2 atoms of P on the right side and 4 atoms on the left side. It can be balance by writing 2 before Mg₃P₂ as shown below:
Mg + P₄ —> 2Mg₃P₂
There are 6 atoms of Mg on the right side and 1 atom on the left side. It can be balance by writing 6 before Mg as shown below:
6Mg + P₄ —> 2Mg₃P₂
Now the equation is balanced.
The coefficients are: 6, 1, 2
Elements >>>> Reactant >>> Product
Magnesium >> 6 >>>>>>>>> 6
Phosphorus >> 4 >>>>>>>>> 4
What is an ionic solid?
Explanation:
In chemistry, an ionic compound is a chemical compound composed of ions held together by electrostatic forces termed ionic bonding. The compound is neutral overall, but consists of positively charged ions called cations and negatively charged ions called anions.
Pls someone help me with this question pls
1 Write the chemical symbols for following elements: Nitrogen-
Phosphorus- bromine- Zinc-Potassium-Magnesium.
Answer:
Look below
Explanation:
Nitrogen: N
Phosphorus: P
Bromine: Br
Zinc: Zn
Potassium: K
Magnesium: Mg
Hope this helps(would be very grateful if you mark this answer branliest bc i need for lvl up)
An alkaline earth hydroxide, M(OH)2, was taken to lab for analysis. The unknown powder was poured into a flask and swirled in room temperature DI water until a saturated solution formed. This solution was then slowly filtered to remove the undissolved solid hydroxide. 28.5 mL of this saturated solution was titrated with 0.173 M HCl (aq). Endpoint required 25.10 mL of the HCl (aq) solution. Calculate the Ksp for this alkaline earth hydroxide.
Answer:
1.77 * 10^-3
Explanation:
From the titration formula;
Let
CA = concentration of acid
CB = concentration of base
VA = volume of acid
VB = volume of base
NA = number of moles of acid
NB = number of moles of base
The equation of the reaction is;
M(OH)2(aq) + 2HCl(aq) -------> MCl2(aq) + 2H2O(l)
So;
CAVA/CBVB= NA/NB
CAVANB = CBVBNA
CB= CAVANB/VBNA
CB= 0.173 * 25.10 * 1/28.5 * 2
CB= 4.3423/57
CB= 0.0762 M
This implies that the solubility of M(OH)2 = 0.0762 M
M(OH)2(s) ----> M^+(aq) + 2OH^-(aq)
So
Ksp = x * (2x)^2
Ksp = 4x^3
x = 0.0762
Ksp= 4(0.0762)^3
Ksp = 1.77 * 10^-3
Please help with this thanks
Answer:
7. Convection
8. Radiation
9. Conduction
Explanation:
Convection is when a fluid, such as air or a liquid, is heated and then travels away from the source, it carries the thermal energy along.
Radiation is the energy that is emitted by matter in the form of photons or electromagnetic waves. So, it is coming off the fire which makes it radiation.
Conduction is the process by which heat or electricity is directly transmitted through a substance when there is a difference of temperature or of electrical potential between adjoining regions, without movement of the material. Because the picture shows different temperatures, it leds to the conclusion that 9 is conduction.
I hope this helps!!
tiny sacs in the lungs where gas exchange takes place are called ____?
Answer:
Alveoli
Explanation:
I hope this helps you.
Compute the mass of KI needed to prepare 500 mL of a 0.750 M solution.
Answer:
62 grams
Explanation:
Molarity=mol/liter
We have mL and Molarity
500 mL * 1 L/1000 mL=0.5
Plug 0.5 in and solve for moles
0.75=mol/0.5
0.75*0.5=0.375 mol
Convert to grams by finding the mass of KI: 39+126.9= 165.9 grams
0.375 mol KI * 165.9 grams KI/1 mol KI= 62.2125 grams
The mass of KI needed is 124.5 grams, this can be calculated by adding the values in molarity formula.
What is Molarity?It is defined as number of moles of solute over volume of solution in liters.
It is given by:
M = n/ V
What information do we have?
Molarity= 0.750 M
Volume = 500 mL= 1 L
Molar mass of KI = 166 g/mol
To find:
Mass of KI=?
On substituting the values:
M= n/V
0.750 M= n/ 1 L
n= 0.750 M* 1l
n= 0.750 moles
Number of moles is the ratio between mass and molar mass.
n= m/M
0.750 moles = m/ 166 g/mol
m= 0.750*166
m= 124.5 grams.
Thus, the mass of KI needed is 124.5 grams.
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oi oi oi oi ewin
.................
what is independent variable
Answer:
a variable (often denoted by x ) whose variation does not depend on that of another.
Explanation:
You can think of independent and dependent variables in terms of cause and effect: an independent variable is the variable you think is the cause, while a dependent variable is the effect. In an experiment, you manipulate the independent variable and measure the outcome in the dependent variable.For example, someone's age might be an independent variable. Other factors (such as what they eat, how much they go to school, how much television they watch) aren't going to change a person's age.
please help me out I’ll give brain to u
Answer:
The answer is streak (A)
Because Streak (the colour of a mineral in its powdered form) is usually obtained by rubbing the mineral on a hard, white surface, such as a tile of unglazed porcelain, so as to yield a line, or streak, of fine powder.
help me plss plss.plsss.plsssplss plsss.plsss plsss plsss plsss
Answer:
1. Distance = 5 cm
Displacement = 1 cm
2. Distance = 7 cm
Displacement = 1 cm
3. Distance = 5 cm
Displacement = -1 cm
4. Distance = 6 cm
Displacement = -2 cm
5. Distance = 4 cm
Displacement = 0 cm
Explanation:
The distance an object travels is a measure of the total ground cobpvered bybthe object without regard to the direction of motion. It is a scalar quantity as it only takes into account magnitude but not the direction of a quantity.
Displacement however, is a measure of how far away or apart an object is from its starting position. It a vector quantity as it takes into account both the magnitude and direction in its measurement.
From the attachment provided, considering forward direction as positive and reverse as negative :
1. When a object moves from point 1 to point 4 and reverses to point 2.:
Distance = from 1 to 4 = 3 cm; from 4 back to 2 = 2 cm; 3 + 2 = 5 cm
Displacement = from 1 to 4 = +3 cm; from 4 back to 2 = -2 cm; 3 - 2 = 1 cm
2. When an object moves from point 1 to 5 and reverses to 2:
Distance = from 1 to 5 = 4cm; from 5 back to 2 = 3 cm; 4 + 3 = 7 cm
Displacement = from 1 to 5 = +4 cm; from 5 back to 2 = -4 cm; 4 - 3 = 1 cm
3. When an object moves from point 1 to 3 and then reverses to 0.
Distance = from 1 to 3 = 2 cm; from 3 back to 0 = 3 cm; 2 + 3 = 5 cm
Displacement = from 1 to 3 = +2 cm; from 3 back to 0 = -3 cm; 2 - 3 = -1 cm
4. When an object moves from point 3 to 5 and then reverses to 1:
Distance = from 3 to 5 = 2 cm; from 5 back to 1 = 4 cm; 2 + 4 = 6 cm
Displacement = from 3 to 5 = +2 cm; from 5 back to 1 = -4 cm; 2 - 4 = -2 cm
5. When an object moves from point 2 to 4 and then reverses to 3.
Distance = from 2 to 4 = 2 cm; from 4 back to 2 = 2 cm; 2 + 2 = 4 cm
Displacement = from 2 to 4 = +2 cm; from 4 back to 2 = -2 cm; 2 - 2 = 0 cm
What is the pH of an aqueous solution with a hydrogen ion concentration of [H+]=8.2×10 −7 M?
Answer:
6.1
Explanation:
From the question given above, the following data were obtained:
Hydrogen ion concentration [H⁺] = 8.2×10¯⁷ M
pH =?
The pH of the solution can be obtained as follow:
pH = –Log [H⁺]
pH = –Log 8.2×10¯⁷
pH = 6.1
Thus, the pH of the solution is 6.1
In another experiment, the student titrated 50.0 mL of 0.100 M HC,H,O, with
0.100 M NaOH(aq). Calculate the pH of the solution at the equivalence point
Answer:
Eqv Pt pH = 8.73
Explanation:
HOAc + NaOH => NaOAc + H₂O
50ml(0.10M HOAc) + 50ml(0.10M NaOH) => 100ml(0.05M NaOAc) + H₂O
For neutralized system, 100ml of 0.05M NaOAc remains
NaOAc => Na⁺ + OAc⁻
Na⁺ + H₂O => No Rxn
OAc⁻ + H₂O => HOAc + OH⁻
C(i) 0.05M ----- 0M 0M
ΔC -x ----- +x +x
C(f) 0.05-x
≅ 0.05M ----- x x
Kb = Kw/Ka = [HOAc][OH⁻]/[OAc⁻] = 1 X 10⁻¹⁴/1.7 X 10⁻⁵ = (x)(x)/(0.05M)
=> x = [OH⁻] = SqrRt(0.05 x 10⁻¹⁴/1.7 x 10⁻⁵) = 5.42 x 10⁻⁶M
=> pOH = -log[OH⁻] = -log(5.42 x 10⁻⁶) = 5.27
pH + pOH = 14 => pH = 14 - pOH = 14 - 5.27 = 8.73 Eqv Pt pH
Addition of sugar to water will result in increase of boiling point
TRUE OR FALSE
Answer:
true
Explanation:
Why reaction between aqueous solutions of hydrochloric acid is commonly referred to as neutralization reaction?
Answer:
The chloride ion has no effect on the acidity of the solution since HCl is a strong acid. Chloride is a very weak base and will not accept a proton to a measurable extent. However, the ammonium ion, the conjugate acid of ammonia, reacts with water and increases the hydronium ion concentration:
Explanation:
Lithium arsenate (Li3AsO4) and iron nitrate (Fe(NO3)3) are dissolved in water. What precipitate would you expect to form? Write the name and formula. (use the solubility table to help)
Salts with nitrates as the anion are generally soluble in water. The question isn’t quite clear: Are we being asked what precipitate would form if these solutions were mixed together? If that’s the case, the reaction would be as follows:
Li3AsO4(aq)+ Fe(NO3)3(aq) → 3LiNO3(aq) + FeAsO4(s).
It is odd that we’re given lithium arsenate dissolved in water to begin with as lithium arsenate should be insoluble. But assuming that it is water-soluble, we can obtain the net ionic equation for the formation of our precipitate:
Fe3+(aq) + [AsO4]3-(aq) → FeAsO4(s).
Our precipitate would be iron(iii) arsenate, FeAsO4.