Question 1: Would dissolving sugar into a cup of coffee be considered a physical or chemical change? Explain.

1. Sodium and water react according to the following equation. If 31.5g of sodium are added to excess water, how many liters of

Vika [28.1K]

<h3> Question 1</h3>

The number of liter of hydrogen gas that are formed at STP is

15.344 L

calculation

2 Na +2 H₂O → 2NaOH +H₂

calculate the moles of Na

moles =mass/molar mass

from periodic table the molar mass of Na = 23 g/mol

moles = 31.5 g /23 g /mol = 1.37 moles

From equation above the mole ratio of Na: H2 is 2:1

therefore the moles of H2 =1.37 x1/2 =0.685 moles

At STP 1 moles of a gas = 22.4 L

0.685 moles = ? L

by cross multiplication

=[ (0.685 moles x 22.4 L) / 1 mole =15.344 L

<h3> Question 2</h3>

The percent yield = 84.77%

calculation

4 Na + O₂ → 2 Na₂O

%yield =actual yield / theoretical yield x 100

Actual yield= 61.8 g

The theoretical yield is calculated as below

Step 1: find the moles of Na

moles = mass /molar mass

from periodic table the molar mass of Na = 23 g/mol

moles = 54.1 g /23 g/mol =2.352 moles

Step 2: use the mole ratio to determine the moles of Na₂O

Na:Na₂O is 4: 2 therefore the moles of Na₂O = 2.352 x 2/4 =1.176 moles

Step 3: find the theoretical mass of Na₂O

mass = moles x molar mass

The molar mass of Na₂O = [(23 x 2 ) + 16] =62 g/mol

mass = 1.176 moles x 62 g/mol = 72.9 g

% yield is therefore = 61.8 g /72.9 x 100 = 84.77%

8 0

3 years ago

List 4 types of information that are given in each box of the periodic table:

omeli [17]

1) the element symbol, and thus name. For example, H is hydrogen, C is carbon and Fe is iron.

2) The atomic number, which is equal to the number of protons in the nucleus.

3) Since each proton has a +1 charge, you can also figure out the number of -1 electrons in the neutral atom.

4) The atomic mass, in atomic mass units, which is an average of 1 or more isotopes of the element.

5 0

3 years ago

Chemistry, please help

Luba_88 [7]

Answer:

Name ; Nickel(ii)Hydroxide

Formula;NI3O6

Explanation:

3 0

3 years ago

NEED HELP ASAFP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!PLEASE!

sp2606 [1]

Here to help! What’s up?

6 0

4 years ago

0.010 moles of carbon C4H10 reacts with oxygon as in the queation 1.76g of carbon dioxide and 0.90 of water are produced. Use th

Sonbull [250]

The coefficients are 2C₄H₁₀ + 13O₂ ⟶ 8CO₂ + 10H₂O

Step 1. Gather all the information in one place.

M_r: 58.12 32.00 44.01 18.02

aC₄H₁₀ + bO₂ ⟶ cCO₂ + dH₂O

m/g: 1.76 0.90

n/mol: 0.010

Step 2. Calculate the mass of C₄H₁₀.

Mass = 0.010 mol C₄H₁₀ × (58.12 g C₄H₁₀/1 mol C₄H₁₀) = 0.581 g C₄H₁₀

Step 3. Calculate the mass of O₂

Mass of C₄H₁₀ + mass of O₂ = mass of CO₂ + mass of H₂O

0.581 g + x g = 1.76 g + 0.90 g

x = 1.76 + 0.90 - 0.581 = 2.079

Our information now has the form:

M_r: 58.12 32.00 44.01 18.02

aC₄H₁₀ + bO₂ ⟶ cCO₂ + dH₂O

m/g: 0.581 2.079 1.76 0.90

n/mol: 0.010

Step 4. Calculate the moles of each compound.

Moles of O₂ = 2.079 g O₂ × (1 mol O₂/32.00 g O₂) = 0.064 97 mol O₂

Moles of CO₂ = 1.76 g CO₂ × (1 mol CO₂/44.01 g CO₂) = 0.040 00 mol CO₂

Moles of H₂O = 0.90 g H₂O × (1 mol H₂O/18.02 g H₂O) = 0.0499 mol H₂O

Our information now has the form:

aC₄H₁₀ + bO₂ ⟶ cCO₂ + dH₂O

n/mol: 0.010 0.064 97 0.040 00 0.0499

Step 5: Calculate the molar ratios of all the compounds.

a:b:c:d = 0.010:0.064 97:0.040 00:0.0499 = 1:6.497:4.000:4.99

= 2 :12.99:8.00:9.98 ≈ 2:13:8:10

∴ a = 2; b = 13; c = 8; d = 10

The balanced equation is

2C₄H₁₀ + 13O₂ ⟶ 8CO₂ + 10H₂O

7 0

3 years ago