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3 years ago

11

What are some ideas for a compound machine for my middle school invention science project that can be useful in people's daily l

ives? I need a explanation of why it's important.

1 answer:

Zanzabum3 years ago

4 0

A toothbrush that has toothpaste in the middle so it comes preloaded. That way it is cleaner and uses more product than normal

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What are the structures in which stars are grouped together?

disa [49]

Answer:

constellations

Explanation:

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3 years ago

What is the wavelength of light in nm with energy of 6.95 x 10^-27 J?

77julia77 [94]

Answer: 27 Hope it helps u

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3 years ago

The mass of a jar of sugar is 11. 9 kg. What is the total mass of 13 jars of sugar?.

Masteriza [31]

Answer:

154.7

Explanation:

11.9kg x 13 = 154.7

5 0

2 years ago

Identify the power of ten that defines each of these prefixes. Input your answers as 10 x where x is the power of ten. nano- ___

Gemiola [76]

<u>Answer:</u> The quantity of every prefix is written below as a power of ten.

<u>Explanation:</u>

In the metric system of measurement, the name of multiples and subdivision of any unit is done by combining the name of the unit with the prefixes.

<u>For Example:</u> deka, hecto and kilo means 10, 100 and 1000 respectively. Deci, centi and milli means one-tenth, one-hundredth, and one-thousandth respectively.

The quantity of these prefixes are written as the power of 10.

For the given prefixes:

<u>Nano:</u> The quantity will be $10^{-9}$

<u>Kilo:</u> The quantity will be $10^3$

<u>Centi:</u> The quantity will be $10^{-2}$

<u>Micro:</u> The quantity will be $10^{-6}$

<u>Milli:</u> The quantity will be $10^{-3}$

<u>Mega:</u> The quantity will be $10^6$

Hence, the quantity of every prefix is written above as a power of ten.

7 0

3 years ago

Hydrobromic acid, HBr, is a strong acid. Hydrofluoric acid, HF, is a weak acid. If you prepared equal

snow_tiger [21]

HBr and HF are both monoprotic Arrhenius acids—that is, in aqueous solution, they dissociate and ionize to give hydrogen ions. A strong acid ionizes completely; a weak acid ionizes partially.

In this case, HBr, being a strong acid, would ionize completely in water to yield H+ and Br- ions. However, HF, being a weak acid, would ionize only to a limited extent: some of the HF molecules will ionize into H+ and F- ions, but most of the HF will remain undissociated.

pH is, by definition, a measurement of the concentration of hydrogen ions in solution (pH = -log[H+]). A higher concentration of hydrogen ions gives a lower pH, while a lower concentration of hydrogen ions gives a higher pH. At 25 °C, a pH of 7 indicates a neutral solution; a pH less than 7 indicates an acidic solution; and a pH greater than 7 indicates a basic solution.

If we have equal concentrations of HBr and HF, then the HBr solution will have a greater concentration of hydrogen ions in solution than the HF solution. Consequently, the pH of the HBr solution will be less than the pH of the HF solution.

Choice A is incorrect: Strong acids like HBr dissociate completely, not partially.

Choice B is incorrect: While the initial concentration of HBr and HF are the same, the H+ concentration in the HBr solution is greater. Since pH is a function of H+ concentration, the pH of the two solutions cannot be the same.

Choice C is correct: A greater H+ concentration gives a lower pH value. The HBr solution has the greater H+ concentration. Thus, the pH of the HBr solution would be less than that of the HF solution.

Choice D is incorrect for the reason why choice C is correct.

4 0

3 years ago