21) Scientists represent elements by using a formulas b. subscripts c. symbols d. words

You use 4.98 g of Na2SO4, how many grams of barium sulfate are produced? Na2+Ba(NO3)2= ?

Kaylis [27]

Answer:

Mass of barium sulfate = 8.17 g

Explanation:

Given data:

Mass of sodium sulfate = 4.98 g

Mass of barium sulfate produced = ?

Solution:

Na₂SO₄ + Ba(NO₃)₂ → BaSO₄ + 2NaNO₃

Moles of sodium sulfate:

Number of moles = mass/molar mass

Number of moles =4.98 g / 142.04 g/mol

Number of moles = 0.035 mol

Now we will compare the moles pf sodium sulfate and with barium sulfate.

Na₂SO₄ : BaSO₄

1 : 1

0.035 : 0.035

Mass of barium sulfate:

Mass = number of moles × molar mass

Mass = 0.035 mol ×233.4 g/mol

Mass = 8.17 g

6 0

3 years ago

The compound methyl butanoate smells like apples. Its percent composition is 58.8% C, 9.9% H, and 31.4% O. What’s the empirical

blsea [12.9K]

To find the empirical formula you would first need to find the moles of each element:

58.8g/ 12.0g = 4.9 mol C

9.9g/ 1.0g = 9.9 mol H

31.4g/ 16.0g = 1.96 O

Then you divide by the smallest number of moles of each:

4.9/1.96 = 2.5

9.9/1.96 = 6

1.96/1.96 = 1

Since there is 2.5, you find the least number that makes each moles a whole number which is 2.

So the empirical formula is C5H12O2.

6 0

3 years ago

Over the years, the thermite reaction has been used for welding railroad rails, in incendiary bombs, and to ignite solid-fuel ro

melamori03 [73]

Answer: The mass of nickel (II) oxide and aluminium that must be used is 18.8 g and 4.54 g respectively.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For nickel:

Given mass of nickel = 14.8 g

Molar mass of nickel = 58.7 g/mol

Putting values in equation 1, we get:

$\text{Moles of nickel}=\frac{14.8g}{58.7g/mol}=0.252mol$

For the given chemical reaction:

$3NiO(s)+2Al(s)\rightarrow 3Ni(l)+Al_2O_3(s)$

For nickel (II) oxide:

By Stoichiometry of the reaction:

3 moles of nickel are produced from 3 moles of nickel (II) oxide

So, 0.252 moles of nickel will be produced from $\frac{3}{3}\times 0.252=0.252mol$ of nickel (II) oxide

Now, calculating the mass of nickel (II) oxide by using equation 1:

Molar mass of nickel (II) oxide = 74.7 g/mol

Moles of nickel (II) oxide = 0.252 moles

Putting values in equation 1, we get:

$0.252mol=\frac{\text{Mass of nickel (II) oxide}}{74.7g/mol}\\\\\text{Mass of nickel (II) oxide}=(0.252mol\times 74.7g/mol)=18.8g$

For aluminium:

By Stoichiometry of the reaction:

3 moles of nickel are produced from 2 moles of aluminium

So, 0.252 moles of nickel will be produced from $\frac{2}{3}\times 0.252=0.168mol$ of aluminium

Now, calculating the mass of aluminium by using equation 1:

Molar mass of aluminium = 27 g/mol

Moles of aluminium = 0.168 moles

Putting values in equation 1, we get:

$0.168mol=\frac{\text{Mass of aluminium}}{27g/mol}\\\\\text{Mass of aluminium}=(0.168mol\times 27g/mol)=4.54g$

Hence, the mass of nickel (II) oxide and aluminium that must be used is 18.8 g and 4.54 g respectively.

4 0

3 years ago

Evaporation and boiling points are the same process, because molecules move from liquid to a gas state

galben [10]

Answer:

false evaporation is change of state

boiling point is temperaturw of liquid

6 0

3 years ago

Read 2 more answers

Suppose two scientists perform the same experiment separately, but their results are very different. What could they do to find

Lynna [10]

They should identify the confounding variable.

Some condition that is not examined by the scientist might alter the experiment result. That condition is called confounding variable. If the method of the experiment same but result is very different, there should be unidentified confounding variable. It could be air humidity, temperature, ventilation, light, time of the year or anything that might not be seen by naked eye.
Try to redo the experiment with controlling variable as much as possible.

5 0

3 years ago