What is the pH of pure water

In which grouping of the periodic table do the elements have simliar properties

STatiana [176]

I would have to say [c]

but it could also be [b]

3 0

3 years ago

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What is the specific heat of a substance if a mass of 10.0 kg increases in temperature from 10.0°C to 70.0°C when 2,520 J of hea

SCORPION-xisa [38]

Heat energy can be calculated by using the specific heat of a substance multiplying it to the mass of the sample and the change in temperature. It is expressed as:
Energy = mCΔT2520= 10.0(C) (70.0 - 10.0)C = 4.2 J/ kg K

7 0

3 years ago

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4. An 82 kg hiker climbs Mt. Humphrey near Flagstaff. During a two hour period, the hiker's

bazaltina [42]

Answer:

$\Delta E = 434253.96\,J$ , $\Delta P = 60.313\,W$

Explanation:

The change in energy is given by the change in gravitational potential energy:

$\Delta E = m\cdot g \cdot \Delta h$

$\Delta E = (82\,kg)\cdot (9.807\,\frac{m}{s^{2}} )\cdot (540\,m)$

$\Delta E = 434253.96\,J$

The average rate of change in terms of time is approximately this:

$\Delta P = \frac{\Delta E}{\Delta t}$

$\Delta P = \frac{434253.96\,J}{(2\,h)\cdot (\frac{3600\,s}{1\,h} )}$

$\Delta P = 60.313\,W$

8 0

2 years ago

An inverted pyramid is being filled with water at a constant rate of 45 cubic centimeters per second. The pyramid, at the top, h

vaieri [72.5K]

Answer:

13.20 cm/s is the rate at which the water level is rising when the water level is 4 cm.

Explanation:

Length of the base = l

Width of the base = w

Height of the pyramid = h

Volume of the pyramid = $V=\frac{1}{3}lwh$

We have:

Rate at which water is filled in cube = $\frac{dV}{dt}= 45 cm^3/s$

Square based pyramid:

l = 6 cm, w = 6 cm, h = 13 cm

Volume of the square based pyramid = V

$V=\frac{1}{3}\times l^2\times h$

$\frac{l}{h}=\frac{6}{13}$

$l=\frac{6h}{13}$

$V=\frac{1}{3}\times (\frac{6h}{13})^2\times h$

$V=\frac{12}{169}h^3$

Differentiating V with respect to dt:

$\frac{dV}{dt}=\frac{d(\frac{12}{169}h^3)}{dt}$

$\frac{dV}{dt}=3\times \frac{12}{169}h^2\times \frac{dh}{dt}$

$45 cm^3/s=3\times \frac{12}{169}h^2\times \frac{dh}{dt}$

$\frac{dh}{dt}=\frac{45 cm^3/s\times 169}{3\times 12\times h^2}$

Putting, h = 4 cm

$\frac{dh}{dt}=\frac{45 cm^3/s\times 169}{3\times 12\times (4 cm)^2}$

$=13.20 cm/s$

13.20 cm/s is the rate at which the water level is rising when the water level is 4 cm.

3 0

2 years ago

A certain reaction with an activation energy of 205 kj/mol was run at 485 k and again at 505 k . what is the ratio of f at the h

lapo4ka [179]

Arrhenius' Law relates activation energy, Ea, rate constant, K, and temperature, T as per this equation:

K (T) = A * e ^ (-Ea / RT), where R is the universal constant of gases and A is a constant which accounts for collision frequency..

Then you can find the ration between K's at two different temperatures as:

K1 = A * e ^ (-Ea / RT1)

K2 = A* e ^(-Ea / RT2)

=> K1 / K2 = e ^ { (-Ea / RT1) - Ea / RT2) }

=> K1 / K2 = e ^ {(-Ea/ R ) *( 1 / T1 - 1 T2) }

=> K1 / K2 = e^ { (-205,000 j/mol / 8.314 j/mol*k )* ( 1 / 505K - 1/ 485K) }

=> K1 / K2 = e ^ (2.0134494) ≈ 7.5

Answer: 7.5

8 0

2 years ago