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Leni [432]
3 years ago
11

Aliyah found a tarnished silver dollar and recalled that tarnish results when metals react with oxygen or sulfur compounds in th

e air. She polished the silver dollar to remove the tarnish until it was shiny again. She also polished a copper bracelet and a gold ring. What physical property of these metals makes them shiny?
A. conductivity

B. ductility

C. luster

D. malleability
Chemistry
1 answer:
snow_lady [41]3 years ago
5 0

Answer:

C.

Explanation:

Luster

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Blast furnaces extra pure iron from the Iron(IIl)oxide in iron ore in a two step sequence. In the first step, carbon and oxygen
OLga [1]

Answer:

5.9 kg  

Explanation:

We must work backwards from the second step to work out the mass of oxygen.

1. Second step

Mᵣ:                                     55.84

            Fe₂O₃ + 3CO  ⟶  2Fe  +  3CO₂

m/kg:                                    7.0

(a) Moles of Fe

\text{Moles of FeO} = \text{7000 g Fe} \times \dfrac{\text{1 mol Fe}}{\text{55.84 g Fe}} = \text{125 mol Fe}

(b) Moles of CO

\text{Moles of CO} = \text{125 mol Fe} \times \dfrac{\text{3 mol CO}}{\text{2 mol Fe}} = \text{188 mol CO}

However, this is the theoretical yield.

The actual yield is 72. %.

We need more CO and Fe₂O₃ to get the theoretical yield of Fe.

(c) Percent yield

\begin{array}{rcl}\text{Percent yield} &=& \dfrac{\text{ actual yield}}{\text{ theoretical yield}} \times 100 \, \%\\\\ 72. \, \% & = & \dfrac{\text{188 mol}}{\text{actual yield}} \times 100 \,\%\\\\0.72 &= &\dfrac{\text{188 mol}}{\text{actual yield}}\\\\\text{Actual yield} & = & \dfrac{\text{188 mol}}{0.72}\\& = & \textbf{261 mol}\\\\\end{array}

We must use 261 mol of CO to get 7.0 kg of Fe.

2. First step

Mᵣ:                32.00

            2C   +  O₂   ⟶  2CO

n/mol:                             261

(a) Moles of O₂

\text{Moles of O}_{2} = \text{261 mol CO} \times \dfrac{\text{1 mol O}_{2}}{\text{2 mol CO}} = \text{131 mol O}_{2}

(b) Mass of O₂

\text{Mass of O}_{2}= \text{131 mol O }_{2} \times \dfrac{\text{32.00 g O}_{2}}{\text{1 mol  O}_{2}} = \text{4180 g O}_{2}

However, this is the theoretical yield.

The actual yield is 71. %.

We need more C and O₂ to get the theoretical yield of CO.

(c) Percent yield

\begin{array}{rcl}71. \, \% & = & \dfrac{\text{188 mol}}{\text{actual yield}} \times 100 \,\%\\\\0.71 &= &\dfrac{\text{4180 g}}{\text{actual yield}}\\\\\text{Actual yield} & = & \dfrac{\text{4180 g}}{0.71}\\\\& = & \text{5900 g}\\& = & \textbf{5.9 kg}\\\end{array}

We need 5.9 kg of O₂ to produce 7.0 kg of Fe.

6 0
4 years ago
What is the molarity of a solution that is 26.0% by mass in phosphoric acid, H3PO4, and that has a density of 1.155 g/mL?
steposvetlana [31]

Answer: The molarity of a solution that is 26.0% by mass in phosphoric acid is 3.06 M

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

Molarity=\frac{n\times 1000}{V_s}

n = moles of solute

V_s =volume of solution in ml

Given : 26.0 g of phosphoric acid in 100 g of solution.

To calculate the moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{26.0g}{98g/mol}=0.265moles

Volume of solution =\frac{\text {Mass of solution}}{\text {Density of solution}}=\frac{100g}{1.155g/ml}=86.6ml

Molarity=\frac{0.265\times 1000}{86.6ml}=3.06M

Molarity of a solution that is 26.0% by mass in phosphoric acid is 3.06 M

8 0
4 years ago
Calculate the vapor pressure of water above a solution prepared by dissolving 28.5 g of glycerin (c3h8o3) in 135 g of water at 3
pshichka [43]
Data:

<span>Solute: 28.5 g of glycerin (C3H8O3)
Solvent: 135 g of water at 343 k.
Vapor pressure of water at 343 k: 233.7 torr.

Quesiton: Vapor pressure of water

Solution:

Raoult's Law: </span><span><span>The vapour pressure of a solution of a non-volatile solute is equal to the vapour pressure of the pure solvent at that temperature  multiplied by its mole fraction.

Formula: p = Xsolvent * P pure solvent

X solvent = moles solvent / moles of solution

molar mass of H2O = 2*1.0g/mol + 16.0 g/mol = 18.0 g/mol

moles of solvent = 135 g of water / 18.0 g/mol = 7.50 mol

molar mass of C3H8O3 = 3*12.0 g/mol + 8*1 g/mol + 3*16g/mol = 92 g/mol

moles of solute = 28.5 g / 92.0 g/mol = 0.310 mol

moles of solution = moles of solute + moles of solvent = 7.50mol + 0.310mol = 7.810 mol

Xsolvent = 7.50mol / 7.81mol = 0.960

p = 233.7 torr * 0.960 = 224.4 torr

Answer: 224.4 torr
</span> </span>
8 0
4 years ago
You purchase several rolls of fiberglass insulation and pay extra for installation. Have you purchased a product or a service?
dmitriy555 [2]
Both bc your buying the product and a service of them installing it
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3 years ago
Pure, a bottled-water manufacturer, is pulled up by regulatory authorities for traces of ammonia in its products. pure forms a t
gulaghasi [49]
The initial report of the team formed by PURE may contain findings similar to the processes used in the disinfection of the water. Usual cases of ammonia presence in water are due to chloramine disinfection process. Also, they should also look into the storage of their facility and the end user which may also have a window of contamination. 
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3 years ago
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