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3 years ago

Which pack has the greatest change in enthalpy, warm packs (such as hand warmers) or cold packs (such as an ice pack)?

1 answer:

3 0

Enthalpy is the change in energy. A cold pack will react endothermically and enthalpy will be positive and a heat pack will have negative enthalpy. You cannot determine which has more change in enthalpy unless you measure the temperature change. Eg. a heat pack went from 25c to 35c will have greater change in enthalpy then a cold pack going from 25 to 20c because the net temperature difference is greater

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A balloon contains 5 L of oxygen at a pressure of 90 kPa. How much oxygen will the balloon contain if the pressure is lowered to

laila [671]

Answer is: volume will be 6,7 L.
Boyle's Law: the pressure volume law - <span> volume of a given amount of gas held varies inversely with the applied pressure when the temperature and mass are constant.
p</span>₁V₁ = p₂V₂.
90 kPa · 5 L = 67 kPa · V₂.
V₂ = 90 kPa · 5 L / 67 kPa.
V₂ = 6,7 L, but same amount of oxygen.

7 0

3 years ago

The standard molar heat of fusion of ice is 6020 j/mol. calculate q, w, and ∆e for melting 1.00 mol of ice at 0◦c and 1.00 atm p

zysi [14]

Answer : q = 6020 J, w = -6020 J, Δe = 0

Solution : Given,

Molar heat of fusion of ice = 6020 J/mole

Number of moles = 1 mole

Pressure = 1 atm

Molar heat of fusion : It is defined as the amount of energy required to melt 1 mole of a substance at its melting point. There is no temperature change.

The relation between heat and molar heat of fusion is,

$q=\Delta H_{fusion}(\frac{Mass}{\text{ Molar mass}})$ (in terms of mass)

or, $q=\Delta H_{fusion}\times Moles$ (in terms of moles)

Now we have to calculate the value of q.

$q=6020J/mole\times 1Mole=6020J$

When temperature is constant then the system behaves isothermally and Δe is a temperature dependent variable.

So, the value of $\Delta e=0$

Now we have to calculate the value of w.

Formula used : $\Delta e=q+w$

where, q is heat required, w is work done and $\Delta e$ is internal energy.

Now put all the given values in above formula, we get

$0=6020J+w$

w = -6020 J

Therefore, q = 6020 J, w = -6020 J, Δe = 0

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3 years ago

Write down your observations of what the pieces of cabbage in the images look like

N76 [4]

They all look like there decaying and was left out or sat inside too long

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2 years ago

True or False - when setting up your conversion problems every numerical value must have a unit on it.

Anastaziya [24]

I think its true but im not 100 percent sure

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3 years ago

The electronegativity is 2.1 for h and 1.9 for pb. based on these electronegativities pbh4 would be expected to

Sedbober [7]

PbH4 will be formed as a result of a polar covalent bond between the H and the Pb.

Since H is more electronegative than the Pb, it is, thus, expected that the H would be able to pull the electron charge towards itself. This will result in the H being negative.

Based on this:
PbH4 would be expected to <span>have polar covalent bonds with a partial negative charges on the H atoms. </span>

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3 years ago