A student dissolves 0.0688 mol of sodium hydroxide in water to make a 0.250 L solution. What is the molarity of the solution?

What is the best reason for a student to remove a dangling bracelet when heating test tubes of acidic solutions in a hot-water b

allsm [11]

So it doesnt touch and create a negative reaction

8 0

3 years ago

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The reaction of Fe₂O₃ with CO produces Fe(s) and CO₂(g). What mass of Fe₂O₃ is required to produce 5.00 kg of Fe(s) if the perce

irina [24]

Answer:

2.75g

Explanation:

Firstly, we write a balanced equation of the reaction.

Fe2O3(s)+3CO(g)-->2Fe(s)+3CO2(g).

Now, we write the formula for the percentage yield.

Percentage yield = Actual yield/theoretical yield * 100%

From the equation, we can see that we have one unknown

We convert the 5kg to g. It must be known that 5kg is 5000g as 1kg equals 1000g.

Now, we are asked to calculate the mass of the iron iii oxide required.

From the balanced equation we can see that 1 mole of iron trioxide yielded 2 moles of Fe.

Now, let’s calculate the mass required. We calculate the actual number of moles of iron produced. This is the mass of iron divided by the molar mass. The atomic mass of iron is 56 amu. The number of moles of iron produced is 5000/56 moles

Since the mole ratio is 1 to 2, the number of moles of iron trioxide thus used is 5000/56 divided by 2 which equals 5000/112 moles.

Now, we proceed to calculate the mass of iron trioxide used. The mass is equal the molar mass multiplied by the number of moles. The molar mass of iron trioxide is 2(56) + 3(16) = 112 + 48 = 160g/mol

The mass thus required to produce 5kg of iron is 5000/112 * 160 which is 3,500g or 3.5kg. We know this to be the theoretical mass, the actual mass is calculated using the formula given above.

78.5 = actual mass/3.5 * 100

Actual mass = (3.5 * 78.5) /100

= 2.75g

6 0

3 years ago

What is the relationship between molar mass in grams per mole (g/mol) and average atomic mass in amu of each element?

navik [9.2K]

Answer:

The molar mass and atomic mass are essentially the same for an element

Explanation:

The molar mass of a substance can be obtained by dividing the mass of the substance by the no of moles of the substance present.

The atomic mass of an element is the number of protons and neutrons present in the substance.

These two measurements usually give the same values because they both make reference to the 1/12th the mass of carbon-12 for their measurement.

Because they both have the same reference point, though they have different calculating procedures, the results obtained will be similar.

8 0

3 years ago

CH4(g)+ 2 O2(g) + CO2(g) + 2 H20 (l)

jasenka [17]

Answer:

<u>∆H° reaction = -890.3 kJ</u>

Explanation:

The given equation is :

$CH_{4}(g)+2O_{2}(g)\rightarrow CO_{2}(g)+2H_{2}O(l)$

Now ,

O2 is in the standard state so its ∆H° is zero.

∆H° is calculated by considering the formation of CO2 , H2O and CH4 .

$C(s)+H_{2}(g)\rightarrow CO_{2}$ ..........∆H°a = -393.5 kJ

$H_{2}+\frac{1}{2}O_{2}\rightarrow H_{2}O(l)$ .....∆H°b = -285.8 kJ

$C+2H_{2}\rightarrow CH_{4}(g)$ ..........∆H°c = -74.8 kJ

Multiply equation of water H2O by 2

and reverse the direction of equation of CH4

Hence the sign of ∆H°c = +74.8 kJ becomes +ve.

We are doing this because CH4 is to be in the reactant side not in the product side.

∆H° reaction = ∆H°a +2(∆H°b) -∆H°c

∆H° reaction = -393.5 - 2(285.8) + 74.8

∆H° reaction = -890.3 kJ

4 0

3 years ago

How many valence electrons do atoms need to be stable? What is the exception?

Gennadij [26K]

In order for an atom to be stable it should have eight valence electrons in order to follow the octet rule the only exception to this rule is hydrogen as the maximum valence electrons it is able to hold is two

8 0

2 years ago