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2 years ago

A block of ice is placed on a hot sidewalk. The ice melts because.

Chemistry

2 answers:

adelina 88 [10]2 years ago

5 0

Answer:

because of heat from the sidewalk

egoroff_w [7]2 years ago

4 0

The ice melts because the heat from the sidewalk caused the solid ice to change into liquid water, or even evaporate.

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Milk of magnesia, a suspension of mg(oh)2 in water, reacts with stomach acid (hcl) in a neutralization reaction. mg(oh)2(s) + 2

defon

Balanced equation for the above reaction is as follows;
Mg(OH)₂ + 2HCl ---> MgCl₂ + 2H₂O
stoichiometry of Mg(OH)₂ to MgCl₂ is 1:1
mass of Mg(OH)₂ reacted - 1.82 g
number of moles of Mg(OH)₂ - 1.82 g/ 58.3 g/mol = 0.0312 mol
number of Mg(OH)₂ moles reacted - number of MgCl₂ moles formed
number of MgCl₂ moles formed - 0.0312 mol
mass of MgCl₂ formed - 0.0312 mol x 95.2 g/mol = 2.97 g
mass of MgCl₂ formed - 2.97 g

5 0

3 years ago

How many sig figs are there 5.00000008

djverab [1.8K]

Answer:

2 sig figs.

Explanation:

Sig Fig Rules:

Any non-zero digit is a significant figure.

Any zeros between 2 non-zero digits are significant figures.

Trailing zeros after the decimal are significant figures.

6 0

3 years ago

15A.4(a) What is the temperature of a two-level system of energy separation equivalent to 400 cm−1 when the population of the up

maksim [4K]

Answer:

T = 525K

Explanation:

The temperature of the two-level system can be calculated using the equation of Boltzmann distribution:

$\frac{N_{i}}{N} = e^{-\Delta E/kT}$ (1)

where Ni: is the number of particles in the state i, N: is the total number of particles, ΔE: is the energy separation between the two levels, k: is the Boltzmann constant, and T: is the temperature of the system

The energy between the two levels (ΔE) is:

$\Delta E = hck$

where h: is the Planck constant, c: is the speed of light and k: is the wavenumber

$\Delta E = 6.63\cdot 10^{-34} J.s \cdot 3\cdot 10^{8}m/s \cdot 4 \cdot 10^{4}m^{-1} = 7.96 \cdot 10^{-21}J$

Solving the equation (1) for T:

$T = \frac{-\Delta E}{k \cdot Ln(N_{i}/N)}$

With Ni = N/3 and k = 1.38x10⁻²³ J/K, the temperature of the two-level system is:

$T = \frac{-7.96 \cdot 10^{-21}J}{1.38 \cdot 10^{-23} J/K \cdot Ln(N/3N)} = 525K$

I hope it helps you!

3 0

3 years ago

Imagine that you have a rectangular swimming pool, but you have no idea how deep it is. You

Ann [662]

To calculate the volume of any rectangular shape,
We can simply multiply length to wide and to depth.
Let d be the depth.
15 x 6 x d = 216
d = 216 / 15 / 6
d = 2.4
Therefore the depth is 2.4m

7 0

2 years ago

The partial pressures of the gases in a mixture are 0.00461 atm O2, 1.78 atm

avanturin [10]

Answer: The total pressure of the mixture is 2.76 atm

Explanation:

According to Dalton's law, the total pressure is the sum of individual pressures.

$p_{total}=p_A+p_B+p_C...$