All categories

2 years ago

What is true about all real machines?

1 answer:

6 0

Answer:It is always greater than the actual mechanical advantage because all machines must overcome friction. The mechanical advantage of a machine may be greater than, less than, or equal to 1, depending on the type of machine.

You might be interested in

For the aqueous solution containing 75 mg of compound C in 1.0 mL of water, what will be the total amount of the solute C that w

Sindrei [870]

Answer:

75 mg

Explanation:

We can write the extraction formula as

x = m/[1 + (1/K)(Vaq/Vo)], where

x = mass extracted

m = total mass of solute

K = distribution coefficient

Vo = volume of organic layer

Vaq = volume of aqueous layer

Data:

m = 75 mg

K = 1.8

Vo = 0.90 mL

Vaq = 1.00 mL

Calculations:

For each extraction,

1 + (1/K)(Vaq/Vo) = 1 + (1/1.8)(1.00/0.90) = 1 + 0.62 = 1.62

x = m/1.62 = 0.618m

So, 61.8 % of the solute is extracted in each step.

In other words, 38.2 % of the solute remains.

Let r = the amount remaining after n extractions. Then

r = m(0.382)^n.

If n = 7,

r = 75(0.382)^7 = 75 × 0.001 18 = 0.088 mg

m = 75 - 0.088 = 75 mg

After seven extractions, 75 mg (99.999 %) of the solute will be extracted.

5 0

3 years ago

Convert the following to moles.

Luda [366]

Use dimensional analysis.
$\frac{60.0 grams NaOH}{1} * \frac{1 mole NaOH}{40.0 amu NaOH} =1.5 moles$

$\frac{2.73 grams NH4Cl}{1} * \frac{1 mole NH4Cl}{53.49 amu NH4Cl} = .051 moles$

Now you try converting moles to grams. All you have to do is start with MOLES (Unlike the previous examples) over 1 then multiply that ratio by the ratio of molar mass over 1 mole. Hope this helps!

6 0

3 years ago

HELP NOW!!!!!! When you put water into a hot metal pan of equal mass, why does the pan cool down more than the water heats up?

Salsk061 [2.6K]

Answer:

Because the specific heat of the metal is less than the specific heat of water.

Explanation:

Hello, happy to help you today!

In this case, we need to analyze a property called "specific heat" which accounts for how much energy is required to increase or decrease the temperature of 1 g of the substance by 1 °C.

In this case, since the specific heat of water is about 4.184 J/g°C and the specific heat of metals in general is greater than zero, of course, but less than one, we can infer that for the same amount of energy, when they are in contact, more grams of metal will be cooled down to those of water heated up, because the specific heat of the metal is less than the specific heat of water.

Best regards!.

8 0

3 years ago

The overall reaction in a chemical cell is shown below as the reaction takes place (look in image)

Doss [256]

According to provided equation it is clear that Zn metal is oxidized from Zn⁰ into Zn²⁺ which means that Zn metal dissolves and forming Zn²⁺ solution so the correct answer is:

mass of the Zn(s) electrode decreases

7 0

3 years ago

Consider the acid-base neutralization reaction H2S(aq) + CN‒(aq) ⇌ HS‒(aq) + HCN(aq) For H2S, pKa = 7.0, and for HCN, pKa = 9.4.

zubka84 [21]

Answer:

Explanation:

To assess the strength of an acid or a base we need to consider the pKa or pKb. For an acid, the lower the pKa, the stronger the acid. For a base, the lower the pKb, the stronger the base.

Which of the following statements is FALSE?

(a) H₂S is a stronger acid than HCN. TRUE. The pKa of H₂S (7.0) is lower than the pKa of HCN (9.4).

(b) CN⁻ is a stronger base than HS⁻. TRUE. We can calculate the pKb of a base when we know the pKa of the conjugate acid using the following expression:

pKa + pKb = 14 ⇒ pKb = 14 - pka

The pKb of CN⁻ (4.6) is lower than the pKb of HS⁻(7.0) so it is a stronger base.

(c) At equilibrium, the equilibrium position favors the reactants. FALSE. In the reaction H₂S(aq) + CN⁻(aq) ⇌ HS⁻(aq) + HCN(aq), H₂S is the stronger acid and CN⁻ is the stronger base, so at the equilibrium the products are favored.

(d) At equilibrium, the equilibrium constant, Kc, is larger than 1. TRUE. Given the products are favored at the equilibrium, the equilibrium constant Kc is expected to be larger than 1 (the numerator is higher than the denominator).

5 0

3 years ago