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2 years ago

A sample of the mineral hematite Iron (III) oxide has a mass of 12.4g. How many moles of the mineral are present?

1 answer:

8 0

Thus problem is providing us with the mass of iron (III) oxide as 12.4 g so the moles are required and found to be 0.0776 mol after the calculations:

<h3>Mole-mass relationships:</h3>

In chemistry, we use mole-mass relationships in order to calculate grams from moles and vice versa. In this case, since we are given the mass of iron (III) oxide as 12.4 g one can calculate the moles by firstly quantifying its molar mass:

$Fe_2O_3\rightarrow 2*55.85 g/mol+3*16.00 g/mol=159.7g/mol$

Then, we prepare a conversion factor in order to cancel out the grams and thus, get moles:

$12.4gFe_2O_3*\frac{1molFe_2O_3}{159.7gFe_2O_3} \\\\=0.0776molFe_2O_3$

Learn more about mole-mass relationships: brainly.com/question/18311376

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A sugar crystal contains approximately 1.4×1017 sucrose (C12H22O11) molecules. What is its mass in milligrams? Express using 2 s

alekssr [168]

Answer:

From the periodic table:

mass of carbon = 12 grams

mass of hydrogen = 1 grams

mass of oxygen = 16 grams

molar mass of surcose = 12(12) + 22(1) + 11(16) = 342 grams

number of molecules = number of moles x Avogadro's number

number of moles = number of molecules / Avogadro's number

number of moles = (2.2x10^17) / (6.02x10^23) = 3.6544 x 10^-7 moles

number of moles = mass / molar mass

mass = number of moles x molar mass

= 1.7 x 10^17/6.022 x 10^23.

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3 years ago

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25.0 mL of an HBr solution were titrated with 29.15 mL of a 0.205 M LiOH solution to reach the equivalence point. What is the mo

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The molarity of HBr solution is 0.239 M

calculation

write the equation for reaction

that is LiOH +HBr → LiBr +H20

find the moles of LiOH used

moles =molarity x volume

=0.205 x 29.15 = 5.976 moles

by use of mole ratio between LiOH :HBr which is 1:1 the moles of HBr is therefore= 5.976 moles

Molarity of HCL= moles /volume

= 5.976/25 = 0.239 M

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3 years ago

Is soil a pure or impure substance?

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Impure substance, because pure would be dirt from the earth

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Write a conclusion statement that addresses the following questions:

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Answer:

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3 years ago

How many moles of gas X are present if the gas has a volume of 2dm³ at room temperature and pressure? Give your answer to 2 deci

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Answer:

Approximately $0.08\; \rm mol$ , assuming that this gas is an ideal gas.

Explanation:

Look up the standard room temperature and pressure: $25\; \rm ^{\circ}C$ and $P = 101.325 \; \rm kPa$ .

The question states that the volume of this gas is $V = 2\; \rm dm^{3}$ .

Convert the unit of all three measures to standard units:

$\begin{aligned} T &= 25\; \rm ^{\circ}C \\ &= (25 + 273.15)\; \rm K \\ &= 293.15\; \rm K\end{aligned}$ .

$\begin{aligned}P &= 101.325\; \rm kPa \\ &= 101.325 \; \rm kPa \times \frac{10^{3}\; \rm Pa}{1\; \rm kPa} \\ &= 1.01325 \times 10^{5}\; \rm Pa\end{aligned}$ .

$\begin{aligned}V &= 2\; \rm dm^{3} \\ &= 2 \; \rm dm^{3} \times \frac{1\; \rm m^{3}}{10^{3}\; \rm dm^{3}} \\ &= 2 \times 10^{-3}\; \rm m^{3}\end{aligned}$ .

Look up the ideal gas constant in the corresponding units: $R \approx 8.31\; \rm m^{3}\cdot Pa \cdot mol^{-1} \cdot K^{-1}$ .

Let $n$ denote the number of moles of this gas in that $V = 2\; \rm dm^{3}$ . By the ideal gas law, if this gas is an ideal gas, then the following equation would hold:

$P \cdot V = n \cdot R \cdot T$ .

Rearrange this equation and solve for $n$ :

$\begin{aligned}n &= \frac{P \cdot V}{R \cdot T} \\ &\approx \frac{1.01325 \times 10^{5}\; {\rm Pa} \times 2 \times 10^{-3}\; {\rm m^{3}}}{8.31 \; {\rm m^{3} \cdot Pa \cdot mol^{-1} \cdot K^{-1}} \times 293.15\; {\rm K}} \\ &\approx 0.08\; \rm mol\end{aligned}$ .

In other words, there is approximately $2\; \rm mol$ of this gas in that $V = 2\; \rm dm^{3}$ .

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3 years ago