At least 2,000 years ago, during the Roman era, pewter was used. The basic ingredients of old pewter were 70% tin and 30% lead. This form of pewter, also referred to as black metal, rapidly lost its lead when exposed to acidic foods.
Pewter stopped using lead when?Older pewters with a higher lead concentration are heavier, tarnish more quickly, and turn a darker shade of silver-grey with time. In 1974, BS5140, which was strengthened in 1994 by the European directive BSEN611, eliminated lead from the composition.
Lead content in antique pewter?Modern pewter is lead-free and safe to use for eating and drinking, however older antique pewter objects may have lead residues.
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help i give more point this time
Answer:
It's a type of chemical bond that emerges because of electrostatic force between electrons and positive metal charges.
Explanation:
I don't know if this is what you are looking for but i don't mind if you copy it.
a student needs to use 0.485 moles of sodium chloride in an experiment how many grams should he measure out in grams. (show work)
Answer:
the answer is 28.4 g NaCl
Explanation:
Help!!!!
I can’t understand this question
Answer:
free points!!!!!!!!!!!!!!
What happens when you mix calcium chloride and hydrogen peroxide?
Answer:
Explanation: When chlorine reacts with hydrogen peroxide, hydrogen peroxide falls apart into water and oxygen. Chlorine gas hydrolyses into hypochlorous acid (, which subsequently into hypochlorite ions . The reaction between hydrogen peroxide and hypochlorite takes place very quickly.
How much heat does it take to raise 100g of aluminum (c= .9 J/gC) from 12.5C to 31C?
Answer:
When two substances having different temperatures are introduced or kept together, heat energy, Q, flows from a substance at higher temperature to a substance at lower temperature. Also, heat continues to be transferred until their temperatures are equalized, at which point the substances are in thermal equilibrium. In a closed system, the amount of energy lost is equal to but opposite the amount of energy gained.
Explanation:
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Answer:
A. 650 moles of sulphur.
B. 30 g of FeS₂
Explanation:
The balanced equation for the reaction is given below:
Fe + 2S —> FeS₂
From the balanced equation above,
1 mole of Fe reacted with 2 moles of S to produce 1 mole of FeS₂.
A. Determination of the mole of sulphur needed for the reaction.
From the balanced equation above,
2 moles of S reacted to produce 1 mole of FeS₂.
Therefore, Xmol of S will react to produce 325 moles of FeS₂ i.e
Xmol of S = 2 × 325
Xmol of S = 650 moles
Thus, 650 moles of sulphur are needed for the reaction.
B. Determination of the mass of FeS₂ produced by the reaction of 0.5 mole of sulphur.
From the balanced equation above,
2 moles of S reacted to produce 1 mole of FeS₂.
Therefore, 0.5 mole of S will react to produce = (0.5 × 1)/2 = 0.25 mole of FeS₂.
Finally, we shall determine the mass of 0.25 mole of FeS₂. This can be obtained as follow:
Mole of FeS₂ = 0.25 mole
Molar mass of FeS₂ = 56 + (32×2)
= 56 + 64
= 120 g/mol
Mass of FeS₂ =?
Mass = mole × molar mass
Mass of FeS₂ = 0.25 × 120
Mass of FeS₂ = 30 g
Thus, 30 g of FeS₂ were obtained from the reaction.
Copper(Ii) Iodate + Potassium Carbonate = Potassium Iodate + copper(I)carbonate into a formula equation ?
Answer:
Cu(IO3)2 + K2CO3 → 2KIO3 + CuCO3
What is the mass of 1.50 mole of (NH4)2CO3?
Answer:
144.12873
Explanation:
Hope this helps you
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回答：
144.12873
説明：
これがお役に立てば幸いです
Answer:
96gm/mole
Explanation:
(NH 4)2CO 3 =2×18+12+3×16=96gm/mole
Which is a property of a covalent compound?
A.being shaped easily
B.good electrical conductivity
C.low melting point
Answer:
c: low melting point
Explanation:
melting point is dependent on intermolecular forces. in covalent compounds, electrons are shared more equally. this means there is less separation of positive and negative charges within the molecules.
Excess Fe reacted with 650mL of 0.75M H3PO4. What mass of hydrogen gas was produced? g H2
Fe + H3PO4 à Fe3(PO4)2 + H2
This is an oxidation-reduction (redox) reaction:
6 HI + 6 e- → 6 H0
(reduction)
3 Fe0 - 6 e- → 3 FeII
(oxidation)
H3PO4 is an oxidizing agent, Fe is a reducing agent
Answer: see pics. Hope it makes sense.
Explanation:
Is heat a from of kinetic or potential energy?
Answer:
its made up of both but I would probably say kinetic
Explanation:
What is the mass of 4.57 x 1021 molecules of ammonia (NH3)?
Answer:
4665.97
Explanation:
(No scammers) can someone help me pls
Answers is - 198 kilo joules
How would I make a biodegradable mask
Answer:
Explanation:
Go to a craft store and buy so me material that are biodegradable
what happens to the rate of a reaction as the reaction progresses
What is metallurgy?
A. Science of minerals.
B. Science of working with metals.
C. Science of breaking down rock.
D. Science of volcanoes.
Answer:
B science of working with metals
Sea, sand, sky, palms – made almost all of
Answer:
sup
Explanation:
Jose was driving to New York City. He traveled 100 miles in the first hour of the trip and 20 miles in the last hour of his trip. Which can we
say about Jose's drive? (speed = distance = time)
A. Jose drove less than 120 miles.
B. Jose drove faster the first hour of his drive.
C. Jose drove slower the first hour of his drive.
D. Jose drove the same speed for the entire drive.
Answer:
b
Explanation:
he drove 5x faster than the time was when he was on the last hour (maybe caught in traffic or wasn't in a rush)
Regions that receive up to 20 inches of rainfall per year are referred to as __________ because they receive more precipitation than most deserts.
semiarid deserts
polar deserts
coastal deserts
subtropical deserts
Answer:
The answer is in fact semi-arid deserts. This just serves as a confirmation cause sometimes the answers be wrong.
Semiarid deserts is the region that receive up to 20 inches of rainfall per year.
What is Rainfall?
This is defined as the amount of precipitation in the form of water droplets that falls onto the surface of Earth from the clouds due to gravity influence.
Semi-arid desert receive more precipitation which is around 20 inches of rainfall than most deserts.
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I NEED HELP PLEASE ASAP THANK YOU!
Answer:
K = °C +273
°C = K - 273
1. 59 °C.
2. 300K.
5. 673K
6. 927 °C
Which of these cannot be
a source of centripetal force?
A. mass
B. friction
C. electric force
D. gravity
Answer:
D. GravityExplanation:
Gravity cannot be a source of centripetal force. Gravity is the force of attraction from between all masses in the universe; especially the attraction of the earth’s mass for bodies near its surface; “gravitation cannot be held responsible for people falling in love” with Albert Einstein.
It manner that is serious and solemn. A solemn and dignified feeling.
Therefore, the correct answer is d. gravity.
If you start with 13 mole H2O and 50 grams of O2 what is the percent yield of H202 if 100 grams of H202 is actually made?
Answer:
94.1 %
Explanation:
We firstly determine the equation:
2H₂O + O₂ → 2H₂O₂
2 moles of water react to 1 mol of oxygen in order to produce 2 moles of oxygen peroxide.
We convert the mass of oxygen to moles:50 g . 1mol /32g = 1.56 mol
Certainly oxygen is the limiting reactant.
2 moles of water react to 1 mol of oxygen.
13 moles of water may react to 13/2 = 6.5 moles. (And we only have 1.56)
As we determine the limiting reactant we continue to the products:
1 mol of O₂ can produce 2 moles of H₂O₂
Then 1.56 moles of O₂ will produce (1.56 . 2) = 3.125 moles
We convert the moles to mass: 3.125 mol . 34 g/mol= 106.25 g
That's the 100% yield or it can be called theoretical yield.
Percent yield = (Yield produced / Theoretical yield) . 100
(100g / 106.25 g) . 100 = 94.1 %
1. Which of the following would not be a good way to describe a body system?
A. Body systems are like computer programs that have to communicate with each
other in order to make the computer work.
B. Body systems are like runners in a marathon who each run alone and don't need the
other runners to finish the race.
C. Body systems are like machines with many different moving parts.
D. Body systems are like individual parts of one big story.
Answer:
the answer would be b
Explanation:
the body sytsem needs to depend on eah other in order to work
Body systems are like runners in a marathon, who each run alone and don't need the other runners to finish the race, is not a good way to describe a body system, hence option B is correct.
How body systems work together?Your digestive tract takes nutrients and water from the food you eat in to your body. The body's cells receive oxygen, water, and nutrients through your circulatory system.
Your skin, excretory system, and respiratory system all function to remove wastes from your cells.
Your body's many systems depend on one another to function properly. While your heart's muscles require oxygen from your lungs to beat, your respiratory system depends on your circulatory system to distribute the oxygen it collects.
Therefore, option B is correct.
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how does dipping an iron bucket in Molten zinc protect it?
Answer:
It forms a barrier that prevents corrosive substances from reaching the underlying steel or iron. The zinc serves as a sacrificial anode so that even if the coating is scratched, the exposed steel will still be protected by the remaining zinc. The zinc protects its base metal by corroding before iron.
Explanation:
Answer:
It protects it from corrosion.
Explanation:
Zinc protects iron and steel from the relentless forces of corrosion. Galvanizing iron and steel by dipping them in molten zinc creates an alloy that can, in the right environmental conditions, protect the iron or steel beneath it for 100 years or more.
A gas has an initial volume of 15 L. If the temperature increases from 330 K to 450 K, what is the new volume.
Answer:
20.(45)L or about 20.4545L
Explanation:
PV = nRT
Where:
P - pressure
V - volume
n - number of particle moles
R - a constant
T - temperature in K
We can assume the P and n (and definitely R) stay the same, so we infer that
[tex]V_1 = \frac{nRT_1}{P} = 15L\\V_2 = \frac{nRT_2}{P}\\V_1 / V_2 = \frac{nRT_1}{P} / \frac{nRT_2}{P} = \frac{T_1}{T_2}\\\\15L / V_2 = \frac{330K}{450K} = \frac{11}{15}\\\\V_2 = 15L \cdot \frac{15}{11} = 20.(45)L[/tex]
I need help with number 17 pls someone pls ???
Answer:
can you pls say what subject it is pls and thank u
Explanation:
Answer:
glass cup as it can trap oxygen from getting in and out meaning that the fire can't grow
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To begin the experiment, 1.65g of methane CH4 is burned in a bomb calorimeter containing 1000 grams of water. The initial temperature of water is 18.98oC. The specific heat of water is 4.184 J/g oC. The heat capacity of the calorimeter is 615 J/ oC . After the reaction the final temperature of the water is 36.38oC.
2. Calculate the change in temperature, ΔT. Show your work. (1pt)
3. Calculate the heat absorbed by water. Use the formula qwater = m • C • ΔT
Show your work (2pts)
4.Calculate the heat absorbed by the Calorimeter. Use the formula:
qcal = Ccal • ΔT Show your work. (2pts)
5. The total heat absorbed by the water and the calorimeter can be calculated by adding the heat calculated in steps 3 and 4. The amount of heat released by the reaction is equal to the amount of heat absorbed with the negative sign as this is an exothermic reaction. (2pts)
a.Using the formula ΔH = - (qcal + qwater ) , calculate the total heat of combustion. Show your work.
b. Convert heat of combustion (answer from part a) from joules to kilojoules. Show your work.
6. Evaluate the information contained in this calculation and complete the following sentence: (2pts)
This calculation shows that burning _______ grams of methane [TAKES IN] / [GIVES OFF] energy (Choose one).
7. The molar mass of methane is 16.04 g/mol. Calculate the number of moles of methane burned in the experiment. Show your work. (2pts)
8. What is the experimental molar heat of combustion in KJ/mol? Show your work. (2pts)
9. The accepted value for the heat of combustion of methane is -890 KJ/mol . Explain why the experimental data might differ from the theoretical value in 2-3 complete sentences. (2pts)
10. Given the formula:
% error= |(theoretical value - experimental value)/theoretical value)| x 100
Calculate the percent error. Show your work. (2pts)
The calorimter is equal to the heat released by the reaction. Calculate the heat released by the reaction.
What is the reaction?The reaction to the news can vary depending on who you are speaking to. For some, the news may be welcomed as a sign of progress and a move in the right direction. Others may be apprehensive, uncertain of the potential outcomes or changes that may come as a result. Some may be angry and frustrated, feeling as though the news has been a long time coming and they have not been given a say in the matter.
1. ΔT = 36.38oC - 18.98oC = 17.4oC
2. qwater = m • C • ΔT
qwater = (1000g)(4.184J/g oC)(17.4oC)
qwater = 71376.8 J
3. qcal = Ccal • ΔT
qcal = (615J/ oC)(17.4oC)
qcal = 10666.1 J
4. qreaction = qwater + qcal
qreaction = 71376.8 J + 10666.1 J
qreaction = 82042.9 J
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10 If Steve was making a solution of ammonium
chloride, how many grams would he have left
undissolved (if any) if he initially placed 140 g of
the chemical into 200 grams of water at 80 °C.
Answer:
8.8g of ammonium chloride would be undissolved.
Explanation:
The solubility of ammonium chloride at 80°C is: 65.6g / 100mL
As the solubility is 65.6g / 100mL, in 200g = 200mL the solubility will be:
65.6g * 2 =
131.2g / 200g
That means the water at this temperature will dissolve 131.2g of ammonium chloride. As were placed 140g, the mass that will be undissolved is:
140g - 131.2g =
8.8g of ammonium chloride would be undissolved
PLEASE ANSWER THIS ASAP I WILL MARK YOU THE BRAINLIEST
The actual subject is Science but they dont have that as a option in pick a subject
Answer:
up to down(1 to 6)
Explanation:
speed:
1,3,4
Velocity:
everything except 1,3,4
How do I perform a titration on coca-cola or Pepsi, when I cannot see the color change because the color is too dark. The indicator is phenolphthalein.
Answer: maybe you need to do very dilute solution?
Explanation: you should have an pH meter instead of indicator.
Phosphoric acid H3PO4 have three ekvivalent points.
Another way could be using a conductivity meter.