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Gelneren [198K]

2 years ago

3

Tummy time' is a supervised time while the infant is awake, during which the infant is laid on his or her stomach to play, which

helps strengthen neck and upper body muscles.
a. True
b. False

2 answers:

RSB [31]2 years ago

8 0

The activity colloquially known as "tummy time" is, in fact, true.

BlackZzzverrR [31]2 years ago

7 0

It is actually true.

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The enthalpy of formation of water is –285.8 kJ/mol. What can be inferred from this statement?

LiRa [457]

A negative formation enthalpy means that the reaction is exothermic, or that heat is released during the process.
(C,)

4 0

2 years ago

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PLEASE HELP!!!!!

Doss [256]

A) an acid because it turns the paper blue

6 0

2 years ago

How many grams of sodium acetate ( molar mass = 83.06 g/mol ) must be added to 1.00 Liter of a 0.200 M acetic acid solution to m

Pie

<u>Answer:</u> The mass of sodium acetate that must be added is 30.23 grams

<u>Explanation:</u>

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$

Molarity of acetic acid solution = 0.200 M

Volume of solution = 1 L

Putting values in above equation, we get:

$0.200M=\frac{\text{Moles of acetic acid}}{1L}\\\\\text{Moles of acetic acid}=(0.200mol/L\times 1L)=0.200mol$

To calculate the pH of acidic buffer, we use the equation given by Henderson Hasselbalch:

$pH=pK_a+\log(\frac{[\text{salt}]}{[\text{acid}]})$

$pH=pK_a+\log(\frac{[CH_3COONa]}{[CH_3COOH]})$

We are given:

$pK_a$ = negative logarithm of acid dissociation constant of acetic acid = 4.74

$[CH_3COONa]=?mol$

$[CH_3COOH]=0.200mol$

pH = 5.00

Putting values in above equation, we get:

$5=4.74+\log(\frac{[CH_3COONa]}{0.200})$

$[CH_3COONa]=0.364mol$

To calculate the mass of sodium acetate for given number of moles, we use the equation:

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

Molar mass of sodium acetate = 83.06 g/mol

Moles of sodium acetate = 0.364 moles

Putting values in above equation, we get:

$0.364mol=\frac{\text{Mass of sodium acetate}}{83.06g/mol}\\\\\text{Mass of sodium acetate}=(0.364mol\times 83.06g/mol)=30.23g$

Hence, the mass of sodium acetate that must be added is 30.23 grams

7 0

2 years ago

Which reaction is endothermic? HCl + NaOH Right arrow. NaCl + H2O + 58 kJ 6CO2 + 12H2O + energy Right arrow. C6H12O6 + 6O2 + 6H2

satela [25.4K]

Answer:

$6CO_2 + 12H_2O + Energy->C_6H_{12}O_6 + 6O_2 + 6H_2O$

Explanation:

-An endothermic reaction is a chemical reaction that gains or absorbs heat from its surrounding in the form of heat.

-During the reaction, the temperature of the surrounding reduces.

-From the reactions given:

$6CO_2 + 12H_2O + Energy-> C_6H_{12}O_6 + 6O_2 + 6H_2O$

is the only endothermic reaction.

$6CO_2 + 12H_2O + Energy->C_6H_{12}O_6 + 6O_2 + 6H_2O$

4 0

2 years ago

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C2H5OH(aq) + MnO− 4 (aq) → Mn2+(aq) + CH3COOH(aq) of acetic acid from ethanol by the action of permanganate ion in acidic soluti

Andreas93 [3]

Answer :

Ethanol $(C_2H_5OH)$ act as reducing agent.

The smallest possible integer coefficient of $MnO_4^-$ in the combined balanced equation is, 4

Explanation :

Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.

Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.

Reducing agent : It is defined as the agent which helps the other substance to reduce and itself gets oxidized. Thus, it will undergo oxidation reaction.

Oxidizing agent : It is defined as the agent which helps the other substance to oxidize and itself gets reduced. Thus, it will undergo reduction reaction.

The given chemical reaction is,

$C_2H_5OH(aq)+MnO_4^-(aq)\rightarrow CH_3COOH(aq)+Mn^{2+}(aq)$

The oxidation-reduction half reaction will be :

Oxidation : $C_2H_6O\rightarrow C_2H_4O_2$

Reduction : $MnO_4^-\rightarrow Mn^{2+}$

Now balance oxygen atom on both side.

Oxidation : $C_2H_6O+H_2O\rightarrow C_2H_4O_2$

Reduction : $MnO_4^-\rightarrow Mn^{2+}+4H_2O$

Now balance hydrogen atom on both side.

Oxidation : $C_2H_6O+H_2O\rightarrow C_2H_4O_2+4H^+$

Reduction : $MnO_4^-+8H^+\rightarrow Mn^{2+}+4H_2O$

Now balance the charge.

Oxidation : $C_2H_6O+H_2O\rightarrow C_2H_4O_2+4H^++4e^-$

Reduction : $MnO_4^-+8H^++5e^-\rightarrow Mn^{2+}+4H_2O$

In order to balance the electrons, we multiply the oxidation reaction by 5 and reduction reaction by 4 and then added both equation, we get the balanced redox reaction.

Oxidation : $5C_2H_6O+5H_2O\rightarrow 5C_2H_4O_2+20H^++20e^-$

Reduction : $4MnO_4^-+32H^++20e^-\rightarrow 4Mn^{2+}+16H_2O$

The balanced chemical equation in acidic medium will be,

$5C_2H_6O+4MnO_4^-+12H^+\rightarrow 5C_2H_4O_2+4Mn^{2+}+11H_2O$

In the redox reaction ethanol act as reducing agent and permanganate ion act as an oxidizing agent.

4 0

2 years ago