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3 years ago

7

Which of the following is an example of a chemical change? A. melting solid gold B. burning hydrogen gas C. breaking a sheet of

glass D. dissolving sugar in water

1 answer:

cestrela7 [59]3 years ago

5 0

The answer is B. Burning hydrogen gas

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when the equation __ cu __h2so4 → __cuso4 __h2o __so2 is correctly balanced, what is the coefficient of cuso4?

schepotkina [342]

<span>1 Cu + 2 H</span>₂<span>SO</span>₄<span> = 1 CuSO</span>₄<span> + 2 H</span>₂<span>O + 1 SO</span>₂

Coefficient od CuSO₄ = 1

hope this helps!

7 0

3 years ago

Nitrogen dioxide is used industrially to produce nitric acid, but it contributes to acid rain and photochemical smog. What volum

zhuklara [117]

Answer:

The volume of nitrogen oxide formed is 35.6L

Explanation:

The reaction of nitric acid with copper is:

Cu(s) + 4HNO₃ → Cu(NO₃)₂ + 2NO₂(g) + 2H₂O(l)

Moles of copper are:

$4.95cm^3\frac{8.95g}{1cm^3} \frac{1mol}{63.55g} = 0.697 moles$

Moles of nitric acid are:

$230mL\frac{1.42g}{mL} \frac{68g}{100g} \frac{1mol}{63.01g}=3.52moles$

As 1 mol of Cu reacts with 4 moles of HNO₃:

0.697 mol Cu × (4mol HNO₃ / 1mol Cu) = 2.79 moles of HNO₃ will react. That means Cu is limiting reactant.

Moles of NO₂ produced are:

0.697 mol Cu × (2mol NO₂ / 1mol Cu) = <em>1.394 moles of NO₂</em>

Using PV = nRT

<em>Where P is pressure (735torr / 760 = 0.967atm); n are moles (1.394mol); R is gas constant (0.082atmL/molK); T is temperature (28.2°C + 273.15 = 301.35K). </em>

Thus, volume is:

V = nRT / P

V = 1.394mol×0.082atmL/molK×301.35K / 0.967atm

V = 35.6L

<em>The volume of nitrogen oxide formed is 35.6L</em>

3 0

3 years ago

How many moles are in 3.4 x 10^23 atoms of O2?

Tamiku [17]

Answer:

5.00 moles..hope it helps

7 0

3 years ago

Silver nitrate reacts with calcium to make calcium nitrate and silver. The reaction is exothermic and produces 18.7 kJ/mol of en

denis-greek [22]

Answer:

1.63 kilo Joules of energy will be produced when 14.8 g of silver nitrate react.

Explanation:

$AgNO_3+Ca\rightarrow Ag+CaNO_3,\Delta H_{rxn}=-18.7 kJ/mol$

Mass of silver nitrate = 14.8 g

Moles of silver nitrate = $\frac{14.8 g}{170 g/mol}=0.08706 mol$

According to reaction, when 1 mole of silver nitrate reacts with 1 mole of calcium it gives 18.7 kJ of heat.

Then amount of heat released when 0.08706 moles of silver nitrate reacts :

$0.08706\times 18.7 kJ=1.628 kJ\approx 1.63 kJ$

1.63 kilo Joules of energy will be produced when 14.8 g of silver nitrate react.

6 0

3 years ago

When two carbon atoms are joined by a double bond, how many electron pairs are shared between the two carbons

NikAS [45]

Answer:

Two (2) electron pairs

Explanation:

The sharing of electron pairs by atoms forms a type of bond called COVALENT bond. Atoms that form covalent bonding (share electrons) do so in order to fill their outermost electron shells, hence, gain chemical stability.

However, when two atoms like carbon share TWO PAIRS of electrons with each other, a DOUBLE BOND is formed. An example is the double bond formed in Ethylene (2HC=CH2). A total of four valence electrons (a pair from each carbon) are shared between the two carbon atoms.

6 0

3 years ago