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3 years ago

8

Which of the following are examples of physical change? Copper oxidizing Iron rusting Carbon dioxide sublimating Water evaporati

ng

1 answer:

kari74 [83]3 years ago

6 0

Carbon dioxide sublimation
water evaporate

physical change is just change between solid/liquid/gas, other two are chemical changes

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When butter is heated it melts and when that melted butter cools and solidifies the process called

avanturin [10]

<span>I'm pretty sure it is called condensation</span>

3 0

3 years ago

A 100.0-mL sample of 1.00 M NaOH is mixed with 50.0 mL of 1.00 M H2SO4 in a large Styrofoam coffee cup calorimeter fitted with a

worty [1.4K]

Answer:

THE ENTHALPY CHANGE IN KJ/MOLE IS +114 KJ/MOLE.

Explanation:

Heat = mass * specific heat capacity * temperature rise

Total volume = 100 + 50 = 150 mL

Total mass = density * volume

Total mass = 1 * 150 mL = 150 g

So therefore, the heat evolved during the reaction is:

Heat = 150 * 4.18 * ( 31.4 - 22.3)

Heat = 150 * 4.18 * 9.1

Heat = 5705.7 J

Equation for the reaction:

2 NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2 H2O(l)

From the equation, 2 moles of NaOH reacts with 1 mole of H2SO4 to produce 1 mole of Na2SO4 and 2 moles of water

50 mL of 1 M of H2SO4 contains

50 * 1 / 1000 mole of acid

= 0.05 mole of acid

The production of 1 mole of water evolved 5705.7 J of heat and hence the enthalpy changein kJ per mole will be:

0.05 mole of H2SO4 produces 5705.7 J of heat

1 mole of H2SO4 will produce 5705.7 / 0.05 J

= 114,114 J / mole

In kj/mole = 114 kJ/mole.

Hence, the enthalpy change of the reaction in kJ /mole is +114 kJ/mole.

5 0

3 years ago

A 52.0 g of Copper (specific heat=0.0923cal/gC) at 25.0C is warmed by the addition of 299 calories of energy. find the final tem

Leto [7]

Answer : The final temperature of the copper is, $87.29^oC$

Solution :

Formula used :

$Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})$

where,

Q = heat gained = 299 cal

m = mass of copper = 52 g

c = specific heat of copper = $0.0923cal/g^oC$

$\Delta T=\text{Change in temperature}$

$T_{final}$ = final temperature = ?

$T_{initial}$ = initial temperature = $25^oC$

Now put all the given values in the above formula, we get the final temperature of copper.

$299cal=52g\times 0.0923cal/g^oC\times (T_{final}-25^oC)$

$T_{final}=87.29^oC$

Therefore, the final temperature of the copper is, $87.29^oC$

4 0

4 years ago

An object with too many is negatively charged.

zubka84 [21]

Answer:Electrons

Explanation:

Because it is!!

3 0

3 years ago

Someone help it’s due today

Kitty [74]

Answer:

All elements are neutral

Explanation:

The plum pudding model of the atom indicated that all elements are neutral. The model was proposed by J.J Thomson after he conducted his experiment on the gas discharge tube.

From the experiment he discovered electrons which he called cathode rays.

Therefore, he suggested the plum pudding model of the atom.

The model describes negatively charge sphere surrounded by positive charges to balance them.

6 0

3 years ago