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4 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:

Zanzabum4 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

You might be interested in

When electrolyzing copper (ll) chloride, what reaction takes place at the anode? What reaction takes place at the cathode?

klemol [59]

Answer:

Copper ions are reduced into copper atoms.

Cu²⁺₍aq₎ + 2e⁻ → Cu₍s₎

Explanation:

During electrolysis, the positive H⁺ and Cu⁺ ions move to the negative cathode and negative OH⁻ and Cl⁻ ions move to the positive anode.

At cathode, copper ions are preferentially discharged due to the low electromotive force required to discharge them compared to the hydrogen ion. The copper ions gain the two electrons lost by the chloride ions when the are discharged. (2 Cl⁻₍aq₎ → Cl₂₍g₎ + 2e⁻)

Thus the half equation is as follows:

Cu²⁺₍aq₎ + 2e⁻ → Cu₍s₎

5 0

3 years ago

Is it really healthy to drink a monster? I mean I feel kinda tired rn

MrRissso [65]

Sugar is really high on a monster and it is bad for your health never drink more than 1. Seriously.

8 0

3 years ago

Read 2 more answers

The molecular weight of table salt, NaCl, is 58.5 g/mol. A tablespoon of salt weighs 6.37 grams. Calculate the number of moles o

cestrela7 [59]

Answer:

The number of moles of salt in one tablespoon is = <u>0.11 mole</u>

<u>Grams </u>cancel each other.

Explanation:

<u>Moles</u> : It is the unit of quantity . It is the mass of the substance present in exactly 12g of C-12.

$moles=\frac{given\ mass}{Molar\ mass}$

<u>Moles Calculation:</u>

Given mass = 6.37 gram

Molar mass = 58.5 g/mol

$moles=\frac{6.37}{58.5}$

= 0.1088

= 0.11 mole

<u>Units calculation</u>

$moles=\frac{given\ mass}{Molar\ mass}$

$moles=\frac{g}{g/mole}$

$moles=\frac{g}{g}\times mole$

<u>g ang g cancels each other </u>

moles = moles

<u>Hence unit = gram (g ) cancel each other.</u>

3 0

3 years ago

Read 2 more answers

An old antacid commercial claimed that each tablet of their product could neutralize 47 times its mass in stomach acid. The acti

butalik [34]

Answer : The number of moles of HCl neutralize is, 0.00824 moles.

Explanation :

The given balanced chemical reaction is:

$NaAl(OH)_2CO_3+4HCl\rightarrow NaCl+AlCl_3+3H_2O+CO_2$

First we have to calculate the moles of $NaAl(OH)_2CO_3$

$\text{Moles of }NaAl(OH)_2CO_3=\frac{\text{Mass of }NaAl(OH)_2CO_3}{\text{Molar mass of }NaAl(OH)_2CO_3}$

Molar mass of $NaAl(OH)_2CO_3$ = 144 g/mol

$\text{Moles of }NaAl(OH)_2CO_3=\frac{0.296g}{144g/mol}=0.00206mol$

Now we have to calculate the moles of HCl.

From the balanced chemical reaction we conclude that,

As, 1 mole of $NaAl(OH)_2CO_3$ react with 4 moles of HCl

So, 0.00206 mole of $NaAl(OH)_2CO_3$ react with $0.00206\times 4=0.00824$ moles of HCl

Thus, the number of moles of HCl neutralize is, 0.00824 moles.

8 0

3 years ago

Gold has an atomic weight of 196.97 g/mol, and a density of 19.3 g/cm3. Approximately how many atoms are in a spherical gold nan

ale4655 [162]

<u>Answer:</u> The number of atoms in spherical gold nano particle are $26.918\times 10^4$

<u>Explanation:</u>

To calculate the volume of sphere, we use the equation:

$V=\frac{4}{3}\pi r^3$

where,

r = radius of the sphere = $10nm=10^{-6}cm$ (Conversion factor: $1nm=10^{-7}cm$ )

Putting values in above equation, we get:

$V=\frac{4}{3}\times 3.14\times (10^{-6})^3\\\\V=4.19\times 10^{-18}cm^3$

To calculate mass of of the substance, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Volume of gold = $4.19\times 10^{-18}cm^3$

Density of gold = $19.3g/cm^3$

Putting values in above equation, we get:

$19.3g/cm^3=\frac{\text{Mass of gold}}{4.19\times 10^{-18}}\\\\\text{Mass of gold}=8.0867\times 10^{-17}g$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Mass of gold = $8.8067\times 10^{-17}g$

Molar mass of gold = 196.97 g/mol

Putting values in above equation, we get:

$\text{Moles of gold}=\frac{8.8067\times 10^{-17}g}{196.97g/mol}=4.47\times 10^{-9}moles$

According to mole concept:

1 mole of an element contains $6.022\time 10^{23}$ number of atom

So, $4.47\times 10^{-19}$ moles of gold will contain = $4.47\times 10^{-19}\times 6.022\times 10^{23}=26.918\times 10^4$ number of atoms.

Hence, the number of atoms in spherical gold nano particle are $26.918\times 10^4$

8 0

3 years ago