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3 years ago

Machines are never 100 percent efficient because some work is used to overcome friction and inertia. True False

Chemistry

2 answers:

ElenaW [278]3 years ago

7 0

False,
machines constantly mess up

Y_Kistochka [10]3 years ago

3 0

This is wrong because machines can make mistakes that why we fix it

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Can anyone help with properties of non-metals?

Katen [24]

Dull (not shiny)
poor conductors of heat and electricity (they are insulators)
weak and brittle (they easily break or shatter when solid)

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3 years ago

Which statement best explains why Earth's outer core is in liquid form?

erik [133]

Answer:

My answer im guessing is "d"

Explanation:

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3 years ago

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Use the graph to answer these questions. The total energy of the reactants is –3,811.92 kJ. –1,273.02 kJ. –2,538.90 kJ.

TEA [102]

Answer:

the first one

Explanation:

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2 years ago

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A 13.5g sample of gold is heated, then placed in a calorimeter containing 60g of water. The temperature of water increases from

sweet-ann [11.9K]

Answer:

$T_i~=163.1$ ºC

Explanation:

We have to start with the variables of the problem:

Mass of water = 60 g

Mass of gold = 13.5 g

Initial temperature of water= 19 ºC

Final temperature of water= 20 ºC

Initial temperature of gold= Unknow

Final temperature of gold= 20 ºC

Specific heat of gold = 0.13J/gºC

Specific heat of water = 4.186 J/g°C

Now if we remember the heat equation:

$Q_H_2_O=m_H_2_O*Cp_H_2_O*deltaT$

$Q_A_u=m_A_u*Cp_A_u*deltaT$

We can relate these equations if we take into account that all heat of gold is transfer to the water, so:

$m_H_2_O*Cp_H_2_O*deltaT=~-~m_A_u*Cp_A_u*deltaT$

Now we can put the values into the equation:

$60~g*4.186~J/g{\circ}C*(20-19)~{\circ}C=-(13.5~g*0.13~J/g{\circ}C*(20-T_i)~{\circ}C)$

Now we can solve for the initial temperature of gold, so:

$T_i~=(\frac{60~g*4.186~J/g{\circ}C*(20-19)~{\circ}C}{13.5~g*0.13~J/g{\circ}C})+20$

$T_i~=163.1$ ºC

I hope it helps!

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3 years ago

Can someone please explain the relationship between the group number, the number of valence electrons lost or gained, and the fo

soldi70 [24.7K]

Ca has 2 valence electrons and F has 7, they would end up having to share electrons but Ca or F has to keep one because in total there are 9 valence elections and only 8 are needed to make this pair "happy". that's all i can provide. i hope it helped some

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3 years ago