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4 years ago

Magnesium oxide can be made by heating magnesium metal in the presence of oxygen. The balanced equation for the reaction is

1 answer:

5 0

$Magnesium+Oxygen-->Magnesium\ Oxide\\\\You\ need\ complement\ factors:\\\\
Oxygen\ is\ always\ in\ two-atoms\ form:\\\\2Mg+O_2--->2MgO\\\\$

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8. Calculate the number of moles of eachsubstance.a. 5.45 x 1026 particles of methane, CH4

Klio2033 [76]

<em>ANSWER</em>

The number of moles of methane is 905.32 moles

STEP-BY-STEP EXPLANATION:

Given information

The number of particles of methane = 5.45 x 10^26 particles

Let x represents the number of moles of methane

To calculate the number of moles, we will be using the below formula

$\text{Number of particles = number of moles x Avogadro's constant}$

Recall that, the Avogadro's constant is given as

$6.02\cdot10^{23}$ $\begin{gathered} 5.45\cdot10^{26}\text{ = x }\cdot\text{ 6.02 }\cdot10^{23} \\ \text{Divide both sides by 6.02 }\cdot10^{23} \\ x\text{ = }\frac{5.45\cdot10^{26}}{6.02\cdot10^{23}} \\ x\text{ = }\frac{5.45}{6.02}\cdot10^{26\text{ - 23}} \\ x\text{ = 0.9053 }\cdot10^3 \\ x\text{ = 905.32 moles} \end{gathered}$

Therefore, the number of moles of methane is 905.32 moles

6 0

2 years ago

What is the mass of 2.65 millimoles of sulfur?

Bas_tet [7]

Divide this problem in to two steps: 1. Convert millimoles to moles. 2. Convert moles to grams.

1.
2.65 mlmol x 1mol/1000mlmol=.00265mol

2.
.00265mol x 32.065g/1 mol=.0850g S

Let me know if you need more explanation on why I used the conversions that I did.

6 0

4 years ago

What is the mass ratio of aluminum to oxygen in aluminum oxide, Al2O3?

liubo4ka [24]

Answer:

9 : 8

Explanation:

Aluminum oxide has the following formula Al₂O₃.

Next, we shall determine the mass of Al and O₂ in Al₂O₃. This can be obtained as follow:

Mass of Al in Al₂O₃ = 2 × 27 = 54 g

Mass of O₂ in Al₂O₃ = 3 × 16 = 48 g

Finally, we shall determine the mass ratio of Al and O₂. This can be obtained as follow:

Mass of Al = 54 g

Mass of O₂ = 48 g

Mass of Al : Mass of O₂ = 54 : 48

Mass of Al : Mass of O₂ = 54 / 48

Mass of Al : Mass of O₂ = 9 / 8

Mass of Al : Mass of O₂ = 9 : 8

Therefore, the mass ratio of Al and O₂ in Al₂O₃ is 9 : 8

5 0

3 years ago

Protein x has an absorptivity of 0.4 ml·mg-1 ·cm-1 at 280 nm. What is the absorbance at 280 nm of a 2.0 mg ·ml-1 solution of pro

Evgen [1.6K]

Absorbance measures the ability of the substance to absorb light at a specific wavelength.

Absorbance is also equal to the product of molar absorptivity, path length and molar concentration.

The mathematical expression is given as:

$A= \epsilon l c$ (1)

where, A = absorbance

$\epsilon$ = molar absorptivity

l = path length

c = molar concentration.

The above formula is said to Beer's Law.

Absorptivity of protein x = $0.4 mLmg^{-1}cm^{-1}$

Path length = 1 cm

Molar concentration = $2.0 mg mL^{-1}$

Put the values in formula (1)

$Absorbance at 280 nm = 0.4 mL mg^{-1}cm^{-1}\times 1 cm \times 2.0 mg mL^{-1}$

= $0.8$

Thus, absorbance at 280 nm = $0.8$

3 0

4 years ago

What is the effect of substituting soluble metal salts such as NaCl and K2CO3 for HCl or (NH4)2CO3 in the qualitative analysis s

larisa [96]

Answer:

D. You can no longer tell if your original sample contained Na+ or K+.

Explanation:

Group reagents are the reagents which are used to separate a whole group of cations from the other groups of cations.

For example, for group 1 , the group reagent is HCl and for group 5, the group reagent is ammonium carbonate.

<u>When sodium chloride and potassium carbonate is used, it means we are contaminating our sample with foreign cations which may interfere in the process of detection. Also, we will not be able to decipher whether the sample has these ions in the initial or not as we have added them.</u>

8 0

3 years ago